Science Investigations Complete Package April

Transcript

Science Investigations Complete Package April 2004 Revision Welcome to the ACES investigating science series. This updated package contains all the current ACES science investigations and support materials for use with the Casio EA-100 Data Analyzer. It can be downloaded free from the Australian ACES web site and consists of: 1. 2. 3. 4. 5. Notes on using the four GET DATA programs One science investigation. Five chemistry investigations. Four physics investigations. Four biology investigations. We hope you find them useful Best wishes, CASIO Education Support. Original Document: 20th September 1999; This revision April 2004. ACES Website: http://www.casioed.net.au Page 1 of 1 Using the GETDATA program with the Casio EA-100/EA-200 Data Analyzers General When loaded into any of the Casio CFX series of graphics calculator, the program 'GET DATA' controls data collection by the Data Analyzer for any activity using any combination of the three supplied probes: 1. Light 2. Temperature 3. Voltage. These probes are always connected to the Data Analyzer unit through any of CH1, CH2 or CH3 sockets. In a typical laboratory or classroom, all students will load a copy of the program from a central source. Within each sub-group of 4 or so students, one calculator will then be used to initiate data collection from an investigation (option 1. New Experiment). This calculator can then be disconnected from the Data Analyzer unit until data collection is complete. Then all students connect to the Data Analyzer unit in turn to download data for individual analysis (using option 2. Download Data). 1. New Experiment This screen is the initial welcome from the program. Choose option 1 or 2 and press EXE. Here 1. New Experiment has been chosen. A reminder to turn on the Data Analyzer unit is shown. Press EXE to continue after the "- Disp -" prompt appears. It is good practice to start in this order: 1. connect probe(s) to Data Analyzer unit 2. connect Data Analyzer unit to calculator 3. turn on Data Analyzer unit 4. start the GET DATA program Enter the number of samples required and press EXE. This can be any integer from 2 to 250. Values outside this range are ignored and either 2 or 250 substituted. www.charliewatson.com Page 1 of 1 Using the GETDATA program with the Casio EA-100/EA-200 Data Analyzers Enter the time interval in seconds between samples and press EXE. The range allowed is 0.001 (1 millisecond) to 16000 (just over 4 hours). Note this is not the total sampling time. The total sampling time is displayed. Abort the program at any stage "- Disp -" is showing by pressing AC/ON followed immediately by EXE to restart from the beginning. A memory check is carried out. If the calculator in use does not have enough memory to download all data after the experiment is over a "Mem ERROR" will be displayed. If this happens, press AC/ON, free up some calculator memory and re-start the program. (Hint: Enter MEM mode and examine usage). When you want data sampling to begin, press EXE and the Data Analyzer unit will flash 'SAMPLING' on its display. Do not press EXE on the calculator to continue until 'DONE' appears on the Data Analyzer unit screen. If data collection will take a long time, the CFX calculator may be turned off and disconnected from the Data Analyzer unit at this point On completion of data collection (DONE appears on the Data Analyzer unit) press EXE. Data is now transferred from the Data Analyzer unit to the calculator. This stage may take up to 1 minute if the maximum number of samples were taken and three probes were used. www.charliewatson.com Page 2 of 2 Using the GETDATA program with the Casio EA-100/EA-200 Data Analyzers Once all data has been transferred to the calculator turn off the Data Analyzer unit to conserve battery life. Press EXE for an automatically scaled scatterplot of time v data. This graph was from an investigation with a light probe. Proceed to the end of the program by pressing EXE. Press MENU followed by the 2 key to enter STAT mode. Once in Statistics mode you can 1. manually edit sampled data to remove any outliers or erroneous data 2. choose different types of graph to display data 3. perform statistical analysis of data 2. Download Data If option 2 was chosen at the start because data collection by the Data Analyzer unit was complete, the reminder to the right will be shown. Data is not lost if the Data Analyzer unit is turned off, but do not unplug the probes. www.charliewatson.com Page 3 of 3 Using the GETDATA program with the Casio EA-100/EA-200 Data Analyzers After pressing EXE to continue, all data is downloaded from Data Analyzer to CFX calculator. This screen indicates 3 probes were used in the experiment. Probes The probes can sample data in the following ranges: 1. Temperature -20?C to 130?C with an accuracy to 0.1?C 2. Light 100 to 999 (measure of relative brightness only) 3. Voltage -10V to +10V with an accuracy to 10mV. Data Analyzer Unit Depending on the probes used, the Data Analyzer unit can drain its four 1.5V batteries fairly quickly. For longer experiments use an external 6V power source. Lists The Lists in the graphics calculator are used to store sampled data as follows: 1. List 1 - time (seconds) 2. List 2 - data from lowest channel used 3. List 3 - data from next lowest channel (if used) 4. List 4 - data from remaining channel (if used) Eg. If the voltage probe was in CH1 and the temperature probe in CH3 then List 2 would contain voltages and List 3 would contain temperatures. The following symbols are used to plot each List: List 2 : a cross List 3 : a square List 4 : a dot www.charliewatson.com Page 4 of 4 Using the GETDATA program with the Casio EA-100/EA-200 Data Analyzers Error messages To clear an error message on the Data Analyzer unit press HALT. To clear an error message on the graphics calculator press AC/ON. Typical causes of the following error messages are: Com ERROR Cable missing or not properly inserted between calculator and Data Analyzer. Make sure cable is inserted at both ends with a 'click'. Mem ERROR Not enough memory free on calculator - you need to free up memory or take fewer samples. Each data point sampled will need 10 bytes. Eg 250 samples ? 10 bytes ? 4 (3 probes + time) = 10000 bytes free needed for data. Graph will need another 4300 or so bytes, so if you check you have 15000 bytes free before starting you should experience no memory problems. Check memory usage in MEM from the MAIN MENU. Syn ERROR The GET DATA program has become corrupted. Delete and load in a fresh version. Ma ERROR Usually caused by the calculator trying to divide by zero - for instance when trying to auto-scale a graph but all data points have the same value. Try manually plotting graph (change in STAT Setup). www.charliewatson.com Page 5 of 5 Using the GETDATA2 program for data observation and collection Introduction GETDATA2 is the big brother of the GET DATA program. If you are new to data logging with the Casio EA-100 Data Analyzer / CFX9850G calculator combination then it is recommended that you spend some time using the basic set of 3 probes supplied with the EA100 and set up your experiments using GET DATA. Once you are familiar with the basics of data logging, then this is the program for you. The program allows you to use any type of probe, any combination of up to four probes, individual calibration or conversion equations for all probes and use of one probe to trigger data collection. Conversion equations are useful to transform the data from one unit to another such as Centigrade to Farenheit. Triggering is essential to capture data over very short time intervals, such as recording the sound of a gunshot. Real-time data logging and graphing is possible where sample intervals are 1-2 seconds or more, enabling the progress of chemical reactions or other experiments to be seen instantly. Variables can also be plotted ‘live’ independently of time, such as pressure v temperature when investigating properties of gases. For long experiments or data sampling activities, once the sampling is underway the calculator can be disconnected from the EA-100 and data retrieved at a later stage. Starting out Transmit the program into your calculator, switch to program mode and start the program. There is no need for the EA-100 unit to be connected to the calculator at this stage. The default opening screen (main menu) is shown. If someone else has been using the program previously, then the parameters may look quite different. Choose Help. Some help screens are included at various stages to jog your memory about the available options. OK returns you back to the main menu. www.charliewatson.com Page 1 of 12 Using the GETDATA2 program for data observation and collection Setting up probes Choose SetP from the main menu to set up probes and then choose which channel on the EA-100 you wish to plug the probe into. Confirm your choice with Yes or No. No is also used to de-select a particular probe/channel. Choose from the selection of probes. Help summarises the selection. Please see the section on use of individual probes at the end of this document for more details. >> displays further choices. After selecting a probe you have the option to calibrate it. For the moment, press No. No selects the default stored calibration as supplied by probe manufacturers and returns you to the start of probe set up. You can now set up more channels or choose DONE to return to the main menu. Calibration and conversion equations are explained later. Help reminds you of the calibration options. www.charliewatson.com Page 2 of 12 Using the GETDATA2 program for data observation and collection Setting up sampling Choose SetS from the main menu. Help explains the options at this stage. ‘Reset all’ clears all channels except CH1, which is set to take 15 samples at 2 second intervals using a temperature probe and with absolute time recording. Help also summarises conditions for real time data graphing. RecT offers the choice of 3 record time options: Off – time will not recorded or stored in a List. Abs – time will be recorded continuously from the start. Rel – time intervals between samples will be recorded. Help summarises the record time options. Choose Intv to set the time interval between samples. Enter a value and press EXE. Choose Smpl to set the number of data samples required. Enter a value and press EXE. www.charliewatson.com Page 3 of 12 Using the GETDATA2 program for data observation and collection All set to GO! Go initiates sampling. The EA-100 must be on and connected to the calculator at this stage. First a memory check is carried out – sampling a large number of points with several probes can use up all your free memory, an annoying thing to discover after the experiment is over! See memory notes below if you get a Mem ERROR. You may also be offered the option for a real-time plot at this stage. See below for details. Next, the EA-100 is initialised ready for sampling. When all is set and experimental equipment is ready press Go. The word ‘Sampling’ will flash on the EA-100 screen. Wait until this stops and ‘Done’ appears (again on the EA-100) before continuing. For long experiments choose the Quit option to return to the main menu and Exit from the program. Data can be retrieved from the EA-100 later using the Get option, freeing up your calculator for other work. If things aren’t working out as planned with your experiment use the Halt option to stop sampling and return to the main menu. www.charliewatson.com Page 4 of 12 Using the GETDATA2 program for data observation and collection Download from the EA-100 Data is transferred to the calculator in two situations. The first is when sampling has finished and you continue by pressing F1. The second is when you choose Get from the main menu, either because you quit the program whilst sampling took place or you wish to download sampled data into several calculators. In this second case, it is important that the channel(s) and record time settings match the original set up otherwise data transfer will fail. Once data is transferred to the lists (in order Time, CH1, CH2, etc where used) the option to Round can be chosen. Rounding is Max value in List Rounding carried out as < 10 2 dp shown: 10 - 100 1 dp > 100 0 dp If record time was set to Abs then the option to graph time v data is available. Choose from a scatterplot, an xy line plot or no graph. The line option is usually best. Here a line plot was chosen for a single probe. If more than one probe was used, each plot is superimposed on top of the others. Pressing SHIFT F1 and using the cursor keys enables tracing along the last graph drawn. Press EXE to return to the main menu. If record time was set to Off and two probes were used then the option to graph one probe v the other is available. Choose from a scatterplot, an xy line plot or no graph. The scatterplot is usually best. Here a scatterplot of distance from light source v light intensity is shown. SHIFT F1 again enables tracing through the points. Press EXE to return to the main menu. www.charliewatson.com Page 5 of 12 Using the GETDATA2 program for data observation and collection Real time sampling If the real time sampling option is available then choose Yes or No. This option is available when: Interval Record Time Probes >1.2s Abs 1 >1.8s Abs 2 >1.8s Off 2 >2.5s Abs 3 Bear in mind that once real time sampling is chosen, it is not possible to later use the Get option to download copies of the data. Sampled data is stored straight to Lists, where it can be later analysed. If Yes was chosen you will need to set up graph scales. Use the EA-100 unit in multimeter mode to get an idea of the range of values expected. For 2 probes with record time Off, both vertical and horizontal scales need setting. This is an example of real time sampling with one probe and record time set to absolute. This is an example of real time sampling with two probes and record time set to off. www.charliewatson.com Page 6 of 12 Using the GETDATA2 program for data observation and collection Exit the program Choosing Exit from the main menu prompts whether you wish to save current settings. Choose Yes or No. This is useful if you plan to repeat the experiment or download data later. The settings are saved in Matrix Z, and the program reminds you of this and gives a couple of warnings. Check you have the latest version of GETDATA2 from the date on this screen. Updates probably exist if your program is more than 6 months old. Check out at the Australian Casio Education website: www.casioed.net.au or the authors site: www.charliewatson.com Probe calibration Choosing Yes from the probe calibration menu leads you through the following screens. Help summarises the options available. Calibration experiments need a minimum of two points. Only linear calibration is currently possible. Enter the number of points and press EXE. www.charliewatson.com Page 7 of 12 Using the GETDATA2 program for data observation and collection Probe calibration (continued) Remove all other probes from the EA-100 before beginning the calibration. Once a steady reading is achieved on the calculator screen hold EXE down until * recorded * appears. Then enter the known value at this calibration point and press EXE. Repeat the above steps for all calibration points. The final screen shows you the calculated linear conversion equation which will automatically be applied to all sampled data by the EA-100 unit. Note that the main menu screen displays a small orange ‘c’ above any channel using either calibrated or custom conversion equations. Custom conversion equations When offered the calibrate probe option, choosing Cstm allows you to enter your own conversion custom equation. Enter a value for ‘a’, press EXE, a value for ‘b’ and press EXE to return to the main menu. A small orange ‘c’ will be displayed just above the channel to indicate the use of a conversion equation. The screen shown is an example of how to take temperature readings in Farenheit instead of the default Centigrade units. See the individual probe information below for more conversion equations for different probes. www.charliewatson.com Page 8 of 12 Using the GETDATA2 program for data observation and collection Using a trigger to initiate data sampling Triggering means you set a value for the probe to reach before sampling begins. For example, you might want to record the air temperature overnight. With the temperature probe in CH1 and a light probe in CH3, you can start sampling when it gets dark by setting the light probe as a trigger. The trigger value would be about 50 and triggering should occur as the light intensity falls down through this value. Alternatively, you might want to find the speed of sound by clapping your hands near the microphone and measuring the time an echo takes to bounce back off a nearby wall. The time would be very short and if sampling was started manually it would be nearly impossible to capture the sounds at the right time. In this case use the microphone in CH3 and set a trigger value of about 3 to rise through before sampling begins. Background noise would not trigger sampling but a loud clap will, which is exactly what is required. To use this option you must connect the trigger probe in CH3. The final option when setting up a probe in CH3 is to use it as a trigger. Choose Yes and type in a value for the triggering to occur at, followed by EXE. Next decide whether the value should be reached by falling or rising and enter the appropriate 0 or 1, followed by EXE. Remember to take into account the use of any conversion or calibration equations set when choosing the trigger value. Note the use of a trigger is shown in the main menu by a red ‘T’ underneath the CH3 probe. www.charliewatson.com Page 9 of 12 Using the GETDATA2 program for data observation and collection A note on calculator memory If you reset your calculator before using this program, once the program is loaded and running the free memory will be around 16 000 bytes. Every number stored in a list needs 10 bytes, which means you should be able to store 1600 numbers in the lists. With a maximum of about 250 numbers per list that equates to 5 full lists, or 250 samples with time recorded + 4 probes. In other words, you should not encounter any memory problems (Mem ERROR). However, using any of the Help options within the program eats up a further 4100 bytes (maximum), so avoid this when using more than 2 probes. Also, any existing programs, matrices, list files, tables, dynamic graphs will all eat up free memory on a calculator which has not been reset first. The use of Memory Reset is therefore recommended before large sample activities are carried out with the GETDATA2 program. A note on probes Temperature The supplied temperature probe does not react quickly to large temperature changes, so beware of this when sampling. Default unit is degrees Centigrade, range from –20 to 130 C. Use custom conversion equation for readings in Farenheit: a = 1.8 b = 32 Kelvin: a = 1 b = 273.2 Light The supplied light probe measures relative intensity with values ranging from 100 to 999. Readings outside this range are often returned but they cannot be relied upon. Voltage The supplied voltage probes return voltages in the range from –10 to 10V. Pressure The Vernier pressure probe has a range of 0 to 690kPa. Use custom conversion equation for readings in Atmospheres: a = 2.20, b = 0 Mm Hg: a = 1670, b = 0 In Hg: a = 65.8, b = 0 Bar: a = 2.23, b = 0 Psi: a = 32.3, b = 0 www.charliewatson.com Page 10 of 12 Using the GETDATA2 program for data observation and collection A note on probes (cont) Microphone The Vernier electret microphone returns a voltage centered on 2.5V (depending on internal batteries – see below). This voltage changes as the pressure on the microphone changes. The EA-100 minimum sample interval is 0.001s, which means that if trying to capture sound waves, the sampled frequencies need to be below about 200Hz. Even at 200Hz, only 5 points will be sampled per wave, which is barely enough. Also, a total of only 10 samples will still show 2 to 3 complete waves. Beware of sample rates which are close to multiples of the frequency. Custom Select these options for any other probes. Use the manufacturers’ specifications to complete a custom conversion equation or carry out a calibration experiment for each one. Motion detector This probe has to be connected via the Sonic port and returns measurements in the range 0.5 to 6m. Use a custom conversion equation for readings in feet with a = 0.305 and b = 0. Note: Experience shows that the state of the EA-100 internal batteries usually effects the accuracy of most probes which use amplifiers. The use of an external 6V power supply for the EA-100 can lead to more consistent and reproducible results. Probes not supported Heart rate The program GETPULSE (free from ACES website) is the best vehicle to explore heart rates. If you want to have a look at how the Heart Rate probe works with GETDATA2, set up a custom channel with 200 samples at 0.03s intervals. You will then see that the amplifier takes around 3 seconds to adjust before a pulse becomes visible. Ph The program GETPH (free from ACES website) is designed for use with the Vernier Ph System. The nature of the amplifier in this system makes it unsuitable for use with GETDATA2. Again, you can set up a custom channel (use the manufacturers calibration equation with a = -3.838 and b = 13.72), but the time the amplifier needs to ‘warm up’ means sampling times of less than a minute produce very inaccurate results. www.charliewatson.com Page 11 of 12 Using the GETDATA2 program for data observation and collection Lists The Lists in the graphics calculator (STAT or LIST mode) are used to store sampled data as follows: 1. List 1 - time (seconds) or data from lowest channel used if record time off. 2. List 2 - data from next channel used 3. List 3 - data from next lowest channel (if used) 4. List 4 - data from remaining channel (if used) 5. List 5 - data from remaining channel (if used) Eg. If the record time was Abs, the voltage probe was in CH1 and the temperature probe in CH3 then List 1 would contain times, List 2 would contain voltages and List 3 would contain temperatures. Error messages To clear an error message on the EA-100 unit press HALT. To clear an error message on the graphics calculator press AC/ON. Typical causes of the following error messages are: Com ERROR Cable missing or not properly inserted between calculator and EA-100. Make sure cable is inserted at both ends with a 'click'. Also error message still on EA-100 screen, probes not in correct sockets or too many probes connected during calibration. Mem ERROR Not enough memory free on calculator - you need to free up memory (see above) or take fewer samples. Check memory usage in MEM from the MAIN MENU. Syn ERROR The GETDATA2 program has become corrupted. Delete and load a fresh version. Ma ERROR Usually caused by the calculator trying to divide by zero - for instance when trying to auto-scale a graph but all data points have the same value. Check your probe set up – are they all in the correct sockets? The program GETDATA2 was first written, documented and released by Charlie Watson in September 1999. It is freely available, together with sample data logging activities for biology, chemistry and physics from the Australian Casio Education Site (www.casioed.net.au). Charlie Watson may be contacted through his website www.charliewatson.com www.charliewatson.com Page 12 of 12 Using the GETPULSE program for heart rate monitoring and data collection Connect the Data Analyzer to a CFX9850G or later calculator, turn both on and start the program GETPULSE. The program carries out a few checks and then displays the ready to start screen. Make sure the Vernier Heart Rate Monitor (HRM-DIN) is connected to CH1 using the DIN adaptor (CBL-DIN). With the ear clip in place press EXE and the Data Analyzer will immediately begin sampling. The whole sampling, data transfer to calculator and pulse calculation cycle takes approx. 15 seconds. If the ear clip is nicely positioned, a plot similar to that shown will be seen. If not, experiment with small changes to its position until a regular waveform is seen. A long hold on F1 (until the screen changes) switches the view to a plot of all pulse values logged so far (history). Sampling will continue. A maximum of 255 values can be stored, which will take at least 1 hour. The vertical axis is fixed from 0 to 200 beats per minute but the horizontal axis re-scales each time, with each tick mark representing approximately one minute. Another long hold on F1 switches back to the pulse waveform view, and so on. www.charliewatson.com Page 1 of 1 Using the GETPULSE program for heart rate monitoring and data collection The program does its best to detect rogue pulse samples, and when it does they are rejected – neither stored nor plotted in history view. The screen shows a rejected sample and indicates that of 10 samples taken so far, 9 have been stored. Low Data Analyzer batteries can cause sampling errors, and the program will indicate when this may be the case. A long press on F6 will stop sampling and end the program. Switch to STAT mode to see: List 1 – Last sample times List 2 – Last sample data List 3 – Elapsed time (minutes) of recorded pulse values. List 4 – Recorded pulse rates GETPULSE was written by Charlie Watson. Email comments or suggestions to him via his website below. www.charliewatson.com Page 2 of 2 Using the GETPH program for pH monitoring and data collection Connect the Data Analyzer to a CFX9850G or later calculator, turn both on and start the program GETPH. Make sure the Vernier pH System consisting of the amplifier box and separate electrode (PH-DIN) is connected to CH1 using the DIN adaptor (CBL-DIN). It is not possible to use any other probe at the same time. You can choose from the sampling default values displayed when the program starts…. Or choose Set to enter the setup view and alter the values one at a time. Rset resets all values and clears any calibration equations. Smpl allows you to change the number of samples. Intv allows you to change the time between samples. Yscl allows you to change the scale on the vertical graph axis to match the expected values during your experiment. Choose Done to return to the main menu. Calibration www.charliewatson.com Choose Cal from the main menu if you want to run a calibration experiment for the probe. This is not usually needed since the program produces accurate results using the built in calibration equation recommended by Vernier. Page 1 of 1 Using the GETPH program for pH monitoring and data collection First enter the number of calibration points you plan to use (minimum of 2) and then a screen similar to the one shown will appear. When you first start using the probe, the electrode amplifier can take up to 1 or 2 minutes to fully ‘warm up’ so allow at least this time before storing the first reading. A pH of 7 will usually give a reading of about 1.7 to 1.8 as shown. A pH of 4 gives a reading of about 2.5 to 2.6. Finally, the calculated calibration equation (which will be used automatically by the program) is displayed. A reminder about the calibration equation is shown after calibration. Choose Go from the main menu to initiate sampling. Wait until the reading shown is steady before choosing Go again. When you first start using the probe, the electrode amplifier can take up to 1 or 2 minutes to fully ‘warm up’ so wait at least this time before starting the experiment. The screen clears and the graph is plotted as points are sampled. When finished press EXE. You can replot the graph (auto-scaled) by choosing Grph from the main menu. Choose Exit and switch to STAT mode to see: List 1 – Last sample times. List 2 – Last sample pH data. GETPH was originally written and documented by Charlie Watson in September 1999. Email comments or suggestions to him via his website below. www.charliewatson.com Page 2 of 2 Science Investigation 1 Which colour is safest? Student Outcomes ♦ The student shows awareness of the need for fair testing and makes simple predictions; collects and organises numerical data and descriptive information using simple tables, diagrams and graphs; identifies main features, patterns and difficulties in the investigation. ♦ The student plans and conducts different types of investigations, taking account of the main variables; collects data using repeat trials or replicates; explains patterns in data or information prepared in different formats; and makes general suggestions for improving the investigation. ♦ The student appreciates that different colours reflect light to varying extents and is aware of the implications that this has for safety at night. Background When walking or cycling at night it is important that motorists can see you. Some clothes are safer to wear than others. The safest colours are those that reflect the most light. In this activity, you have been given a light source, a selection of fabrics and a Casio Data Analyzer with probes. Your task is to rank the colours from most safe to least safe. Equipment • • • • • • • Casio EA-100 Data Analyzer Casio CFX9850 graphics calculator with GET DATA loaded Voltage probes as supplied with the EA-100 unit Light probe as supplied with the EA-100 unit Light source. Eg: microscope lamp or light box Retort stand with boss-head and clamp Pieces of non-gloss card or paper of various colours Planning Hypothesis Which colour do you think is safest? Rank the colours in the order that you think is correct from the most safe to the least safe. Be sure to explain why you ranked them in that order. Making the Experiment Fair Which variable will you be investigating? i.e. what things about the experiment will you change? Page 1 of 3 Science Investigation 1 Which colour is safest? Which variables will you be controlling? i.e. what things about the experiment will you keep the same? Measurement State what probe you plan to use and explain with a diagram how you will use the probe along with the other equipment to test your hypothesis. How many data points will you collect for each colour and what time interval will you have between data points? Conducting Carefully set up your experiment, ensuring that it is as fair as possible. Take some trial readings. Describe briefly how successful your trial was and any changes that you had to make. Now carry out your experiment, recording all of your sample data into an appropriate data files in your calculator. Processing of Results Use your calculator to determine the average intensity of the reflected light for each fabric. Record these averages or use a link-cable to copy your data to a PC and present them in your report. Present your data graphically (ideally using a spreadsheet). Discuss any patterns from your data and whether or not your initial hypothesis has been supported. Write a conclusion for this investigation and try to use your Science Knowledge to explain your findings . Evaluating Did your investigation give you the sort of results that you expected? Explain all of the difficulties that you experienced during the investigation, any sources of error and how you could improve the experiment. Page 2 of 3 Science Investigation 1 Which colour is safest? Teacher notes and sample data Typical Data This table shows data collected with 10 samples over 0.5 second intervals. This means data was collected for 5 seconds for each colour. This table shows the data for purple paper, with the probe and light source both 10 cm from the paper. This table shows the same data as above, with list 3 containing the mean of list 2. The average intensity of the reflected light for the purple paper was 313. This table shows data recorded for white paper. The average intensity of the reflected light for the white paper was 541. Comments As this is an open-ended investigation it is not assumed that student data will resemble the above data, it is given only as a guide. The students may design an experiment quite different to the one we described. We found that the experiment worked very well with the set-up shown in the picture. Depending on the ability of your students, you may choose to remove the picture before providing the worksheet, as it may focus their planning too much. It is a good idea to use non-gloss paper to reduce error. Page 3 of 3 Chemistry Investigation 1 Latent Heat of Fusion of Napthalene Student Outcomes ♦ Describe solid/liquid and liquid/vapour equilibria at the melting and boiling point. ♦ Use the Kinetic Theory to explain the characteristic properties of solids, liquids and gases. ♦ Describe and explain melting/solidification in terms of the Kinetic Theory. ♦ Describe and explain the shapes of the cooling/heating curves of pure substances. Background The kinetic theory suggests that in order to change a solid into a liquid, heat energy must be provided to free the molecules from the lattice forces that hold them together. When a liquid solidifies, the heat needed to free the molecules from the lattice forces is given out again. The heat energy difference between the solid and liquid states is called latent heat of fusion. In this investigation you will explore the change of state from liquid to solid of napthalene and identify it's melting point. Equipment • • • • • • Casio EA-100 Data Analyzer. Temperature probe as supplied with EA-100 unit. SB-62 cable as supplied with EA-100 unit to link EA-100 to calculator. Casio CFX9850 graphics calculator with GET DATA program loaded. Test-tube, beaker, tripod, gauze, Bunsen burner, clamp and stand. Napthalene. Procedure 1. Put about 3-4cm depth of napthalene into the test-tube and clamp it in a beaker that is half filled with water. 2. Heat the beaker on a gauze supported on a tripod. When the napthalene has completely melted continue heating for another minute or so and then remove the heat. 3. Lift the clamp and test-tube free of the water and wipe the tube dry. 4. Insert the temperature probe into the napthalene and start the GET DATA program on your calculator, choosing 150 samples at 10 second intervals. The program will record data for the next 25 minutes. If the napthalene does not totally solidify in this time repeat steps 2, 3 and 4 but choose more than 10 seconds for the sampling interval. Page 1 of 3 Chemistry Investigation 1 Latent Heat of Fusion of Napthalene 5. When data collection has finished, remove the temperature probe by replacing the testtube into the beaker of hot water and remelting the napthalene. Processing of Results Graph your results with time (List 1) on the horizontal axis and temperature (List 2) on the vertical axis. Use your graph to determine the melting point of napthalene. Questions 1. Describe the shape of your graph and label the various states of the napthalene on your line. 2. Explain how you determined the melting point of napthalene. 3. Explain the shape of your graph using the kinetic theory. How does your graph support the idea of latent heat of fusion? 4. How could you use the melting point you found in this investigation to determine the purity of the napthalene you used? Explain your answer. Extensions Repeat the investigation but start with the temperature probe in solid napthalene. Record the temperature as the napthalene heats up and melts in the water bath. How do your results compare with those for cooling? Investigate the effect of impurities added to napthalene (eg camphor) on the melting point. Page 2 of 3 Chemistry Investigation 1 Latent Heat of Fusion of Napthalene Teacher notes and sample data Typical Results These results were recorded over 25 minutes by taking 150 samples at intervals of 10 seconds. The initial temperature was just under 100°C. It fell to 74°C as shown after 450 seconds (7-8 minutes) - the melting point - and tailed off to 45°C after 25 minutes. Comments The greater the amount of napthalene in the test tube the flatter the middle section of the graph becomes. The trade off is that the cooling then takes longer. Avoid too little napthalene at any rate as this will almost certainly lead to no 'flat' part on the graph. Use the multimeter mode of the data analyzer to check that the temperature of the napthalene is around 100°C before starting the data collection. Stress the care needed to keep the temperature probe cable away from any heat source. Page 3 of 3 Chemistry Investigation 2 The lead-acid battery Student Outcomes ♦ Describe an electrochemical cell as a system for transforming the chemical potential energy of an oxidation-reduction reaction to electrical energy. ♦ Define the 'anode' as the electrode at which oxidation occurs and the 'cathode' as the electrode at which reduction occurs. ♦ Define electromotive force (EMF) of a cell. ♦ Describe and explain how an electrochemical cell can be considered as two half-cells. ♦ Describe the construction and operation of the lead-acid accumulator. Background The lead-acid battery is an example of a rechargeable cell . This means that it can be restored to its original condition by using an external voltage source to reverse the cell reaction, this is known as charging the battery. In this investigation you will study the lead acid cell and in particular how the charging time affects the time taken for the battery to discharge. Equipment • • • • • • • • • • Casio EA-100 Data Analyzer Casio CFX9850 graphics calculator with GET DATA loaded Voltage probes as supplied with the EA100 unit 100 mL beaker Two lead plates mounted on a piece of wood so that they are 1 cm apart, the piece of wood should be wide enough so that it can suspend the lead plates in the beaker (see photograph of equipment). Low wattage globe (available from Jaycar Electronics) Power pack (0-12 V) Two crocodile clips 5 molL-1 sulfuric acid (100 mL) emery paper Procedure 1. Clean the lead electrodes with the emery paper. 2. Place the electrodes in the beaker and add 80 mL of the 5 molL-1 H2SO4. 3. Connect the globe to the electrodes and record your observations, then disconnect the globe. 4. Connect the power supply to the electrodes and set it to 6 V DC, record on the electrodes which is positive and which is negative. Page 1 of 3 Chemistry Investigation 2 The lead-acid battery 5. Switch on the power supply and charge the cell for exactly 5 minutes, the cell is now charged. 6. You will now use your Casio data analyzer to record how the output voltage varies as the cell is discharged through a light globe. 7. Connect the voltage probes to CH1on the data analyzer. 8. Using a link cable, connect the data analyzer to your graphic calculator. 9. Connect the voltage probes to the electrodes (remember: red is positive!) and start the GET DATA program on your calculator, choosing 250 samples at 0.15 second intervals. This will record data for 37 seconds. Start recording data. 10. As soon as data starts being recorded, connect the battery across the electrodes (parallel with the voltage probes) to light the globe. Record any visual observations during the discharge period. 11. Once data recording has stopped, save the data file and repeat steps 5-10 for a charging time of 15 minutes. Processing of Results Use your calculator to produce two graphs of voltage against time. One graph for the 5 minute recharge and one graph for the 15 minute recharge. If you have a PC in the lab, use a PC link cable to screen dump your graphs so that they can be printed and used in your write-up later. Questions 1. Write the anode and cathode reactions and overall reactions for the cell during charging and discharging. 2. Explain the relationship between the charging and discharging equations. 3. Explain how the pH of the sulfuric acid solution would vary during charging and discharging. 4. While the cell was being charged, the negative electrode was acting as the cathode. Was the negative electrode always the cathode? Explain your answer. 5. Was the 15 minute recharge 3 times better than the 5 minute recharge? Explain your answer. 6. What was the maximum EMF produced by your cell? A car starting motor requires 12 volts. How could such cells be used to start a car? Extensions Plan and carry out an experiment which investigates how the pH of the sulfuric acid changes in a lead-acid battery while being charged and discharged. Use your text or Chemistry laboratory manual to find out how to produce a model dry cell (Leclance Cell). Plan and carry out an experiment to find out how cell size affects EMF produced and the total energy stored in the battery. Page 2 of 3 Chemistry Investigation 2 The lead-acid battery Teacher notes and sample data Typical Data We collected this data with 250 samples at 0.1 second intervals giving a logging time of 25 seconds. Comments The data logging time will very much depend on the current drawn during discharge. You will need to vary this if you are using a load other than that recommended. We first tried the experiment with a standard 2.5 V globe and found that it fully discharged within a few seconds. Then we tried an LED, this gave an excellent discharge time; however, because of its semi-conductor nature, stopped drawing current as soon as it stopped glowing, so the graph flattened at the minimum operating voltage for the LED. We found that the small low wattage globe (from Jaycar Electronics) did the job nicely. They come pre-attached to thin wire leads. We found that the globe tended to switch off rather than fade out gradually. Presumably this is a characteristic of small-scale cells. If the power supply trips out during charging (or worse blows a fuse), try lowering the voltage and/or separating the lead electrodes further. Cover the beaker during charging as it bubbles furiously. Page 3 of 3 Chemistry Investigation 3 Acid-base reactions Student Outcomes ♦ Define neutralisation as the reaction of an acid with a base ♦ Describe the formation of salts by neutralisation between acids and bases. ♦ Use the concept of hydrolysis to explain and predict the acid/base properties of the salts formed from a neutralisation reaction. ♦ Relate the position of equivalence point to the acid/base properties of salts formed from a neutralisation reaction. ♦ Use a pipette, burette and pH probe in volumetric analysis Background When an acid is gradually added to a base (or vice versa), there is usually a dramatic change in the pH of the solution at the instant of neutralisation. This point is known as the equivalence point and represents the point when all OH- ions in the solution have been reacted with H+ ions. If acid is added after this point, H+ ions will be present in excess and the pH will be dramatically lower than it was before equivalence. If we know the concentration of one reactant, by observing the position of the equivalence point, it is possible to find the concentration of an unknown reactant. This process is known as a titration. The pH of the equivalence point depends on the acid/base properties of the salt produced in the titration. So, depending on the reactants used, the pH of the equivalence point can vary considerably. With traditional titration methods, you would need to identify the pH of the salt produced by the titration and choose an appropriate indicator, whose end-point matches the equivalence point. By using a data logging approach, the pH can be recorded progressively during the titration. In this investigation you will produce pH curves for 4 different titrations and analyse these curves to determine the acid/base properties of the salts produced. You will do this by logging the pH of various basic solutions while an acid is continuously added. Equipment • • • • • • • • • Casio EA-100 Data Analyser. Casio CFX9850 graphics calculator with GETPH program loaded. Vernier pH System (PH-DIN) and CBL-DIN adaptor. Copy of notes ‘Using the GETPH program’ 25.0 mL pipette. burette and stand. 250 mL conical flask. 2 x 100 mL beakers. distilled water bottle. Page 1 of 4 Chemistry Investigation 3 Acid-base reactions • • • • • funnel. 0.10 molL-1 hydrochloric acid solution. 0.10 molL-1 sodium hydroxide solution. 0.10 molL-1 ammonia solution. 0.10 molL-1 ethanoic acid solution. Procedure 1. Clean all glassware thoroughly, finally rinsing the burette with the hydrochloric acid solution. While cleaning the burette, you should time the flow-rate from the burette. This is necessary as later you will be plotting pH against time and we want the time axis to approximate the volume of acid added. 2. Fill the burette with 0.10 molL-1 HCl(aq) 3. Pipette 25.0 mL of 0.10 molL-1 NaOH(aq) into the conical flask, insert the pH probe into the flask and place it under the burette. 4. Connect the pH probe to CH1 on the data analyser. 5. Using a link cable, connect the data analyser to your graphic calculator and start the GETPH program. 6. Set up sampling as shown in the screen. 7. Choose Go and wait until a steady reading is shown on the calculator screen. Waiting is necessary to allow the pH probe and amplifier to reach equilibrium before the acid is added. Then choose Go again to start sampling and open the burette and continually agitate the conical flask as acid is being added. 8. When the data has been logged, you should have a pH curve for the titration. Use a pclink cable to capture a screen-dump from your calculator and save this on a PC so you can use it in analysis later. 9. Repeat steps 1-8 for the following reagents: 0.10 molL-1 HCl(aq) vs 0.10 molL-1 NH3(aq and 0.10 molL-1HCl(aq) vs 0.10 molL-1 CH3COOH(aq) Processing of Results Depending on how you are presenting your findings, you may need to print out your pH curves for inclusion in your report. Otherwise, leave them on disk so that you can paste them into an electronic report. Using the Grph option, you can trace along the last curve plotted and note pH readings at different stages of the titration. Alternatively, exit the program and go to STAT mode and examine the sampled pH data in List 2. Page 2 of 4 Chemistry Investigation 3 Acid-base reactions Questions 1. Describe the differences between the equivalence points in your three titrations. 2. From your observations, determine acid/base nature of the equivalence points in your three titrations. Relate this to the strength of the reagents used. 3. Where appropriate, use hydrolysis equations to explain the acid/base properties of the three equivalence points. Remember this depends on the nature of the salt produced. Extensions Carry out the same procedure for a titration between ammonia solution and ethanoic acid solution. Describe the shape of the curve produced and compare it to the three curves produced in the investigation. Research the concept of buffering and use this information to explain your observations in this last titration. Explain why ethanoic acid should not be used to standardise a solution of ammonia. Page 3 of 4 Chemistry Investigation 3 Acid-base reactions Teacher Notes Typical Data This curve was produced by titrating HCl(aq) with NaOH(aq). The settings were the same as those outlined in the body of this investigation. The second screen is the first re-scaled and re-plotted using the Grph option. You can trace along the curve using the cursor keys (SHIFT F1 first). It shows that after 32 seconds the pH was 6.7. Comments The equivalence point is more dramatic the slower the acid is added. Students should be encouraged to vary the parameters to allow for a slower flow rate and observe the increase in accuracy. It is very important to continually agitate the conical flask (as with any titration). It is also very important that the pH probe is always immersed in liquid. It may be necessary to add distilled water after adding the base to ensure this. Typically, 20mL from a burette will empty in approximately 30s. These values allow students to recalibrate the x-axis from time to volume of HCl added. The extension activity demonstrates the concept of buffering very nicely, as even with a slow flow rate, there is no definite equivalence point. This is an excellent way to illustrate to students why weak reagents are never titrated against each other. These results were obtained with the factory settings for calibration of the pH probe (this calibration is automatic in the GETPH program). If your results seem inaccurate, you may need to calibrate your pH probe using the Cal option using two solutions of known pH, eg: buffer solutions of pH 4 and pH 10 would produce an excellent calibration. Page 4 of 4 Chemistry Investigation 4 Boyle's Law Student Outcomes ♦ ♦ ♦ ♦ Describe Boyle's Law for Ideal Gases. Collect and process data to plot a pressure-volume graph. Analyse data to independently derive Boyle's Law. Describe the relationship between pressure and volume for a gas in terms of the Kinetic Theory. ♦ Cite everyday examples where an understanding of Boyle's Law is important. Background The behaviour of all gases can be described in terms of the Kinetic Theory. In this investigation you will study the relationship between the volume and pressure of a gas. This will be done by logging the pressure (kPa) against volume(cc or mL). We are actually plotting against time and not volume, but if the volume is increased once every two seconds, the time axis will represent volume. Equipment • • • Casio EA-100 Data Analyser. Casio CFX9850 graphics calculator with GETDATA2 program loaded. Vernier Pressure Sensor with syringe and connections as supplied and CBL-DIN adaptor. Procedure 1. Using the DIN adapter, connect the pressure sensor to the EA-100. 2. Expel all air from the syringe and connect it to the pressure sensor. 3. Ensure that the small tap is allowing air flow from the pressure sensor to the syringe (ie: the tap should be perpendicular to the tubing). 4. Use a link cable to connect the EA-100 to your Graphic Calculator. 5. Run the GETDATA2 program and set up sampling as shown. 6. When you begin data sampling, choose the real time plot option with a scales y-min of 0 and a y-max of 110. Choose GO and start collecting data, ensuring that the syringe is withdrawn 1cc every 2 seconds. The sample number will be displayed on the top right-hand corner of the screen and one student should instruct the other when to move the plunger. You may need to repeat the experiment a few times to produce quality results. Page 1 of 3 Chemistry Investigation 4 Boyle's Law Processing of Results Once the experiment has finished, enter the STAT mode of your calculator. You will need to delete the first pair of data points as the calculator will have difficulty handling the data. Why do you think this is? Plot a scatter graph of your data. What does it show? Now use the calculator to determine a power function which best approximates the data. ie: a function of the form y = axb. Record this function and choose DRAW to see how well your relationship matches the data. You may wish to use a pc-link cable to transfer screen dumps of your graphs and equation for inclusion in your write-up. Questions 1. What did the graph of pressure against volume tell you about the relationship between the two quantities? 2. What function did you find best approximated the data? What is the name given to a graph of such a function. 3. Write your equation in terms of P and V. 4. Use your equation to predict the volume of gas in the syringe if the pressure was lowered to 0.01 kPa. 5. Compare your equation to Boyle's Law. 6. Relate your results from this investigation to the Kinetic Theory. 7. Explain the consequences of Boyle's Law for scuba diving 8. Make a list of the errors in this experiment. Extensions Think of possible ways of improving the accuracy of this investigation. Your improvements should focus on the initial volume of air in the tubing between the syringe and the pressure sensor. You should then run the experiment again and manipulate the data as necessary. Then re-process the data and find a more accurate relationship between pressure and volume. Page 2 of 3 Chemistry Investigation 4 Boyle's Law Teacher Notes Typical Data The figures here represent the results for the settings listed in the body of the investigation. As you can see, the results are pleasing and the power function produced very closely matched the data. Comments As you can see, the equation was of the form P = kV-1.6. Of course it would have been much nicer if the it was P = kV-1 !! This investigation is very simple but has one major inaccuracy; the initial volume is taken to be 0cc, with a corresponding pressure equal to 100kPa (atmospheic pressure). Students should be encouraged to measure (or at least estimate) the volume of air in the tube between the pressure sensor and the syringe and add this to the all of the data points in list 1. This would improve the results considerably, and the pressure should then approach infinity as the volume approaches zero. As an alternative they could wait a little longer before the syringe is withdrawn, and then delete the first few data points from list 1. This would simulate having an initial value for the volume. It takes less force to withdraw the syringe than compress 20 cc of trapped air. This means the time scale can then directly relate to the volume. However, students could easily compress the syringe instead and make corresponding changes to the data in list 1 to allow for this. ie: t = 0 would correspond to V = 20 cc and so on. Page 3 of 3 Chemistry Investigation 5 The Constant Volume Law Student Outcomes ♦ ♦ ♦ ♦ ♦ Relate the Constant Volume Law to the Kinetic Theory. Describe the Constant Volume Law for Ideal Gases. Collect and process data to plot a pressure-temperature graph. Analyse data to independently derive the Constant Volume Law. Describe the relationship between pressure and temperature for a gas in terms of the Kinetic Theory. ♦ Cite everyday examples where an understanding of the Constant Volume Law is important. Background The behaviour of all gases can be described in terms of the Kinetic Theory. In this investigation you will study the relationship between the temperature and pressure for a gas and relate this relationship to the Kinetic Theory. You will do this by logging the pressure (kPa) against temperature (ºC). Equipment • • • • • • • Casio EA-100 Data Analyser. Casio CFX9850 graphics calculator with GETDATA2 program loaded. Vernier Pressure Sensor with stopper and connecting tube as supplied and CBL-DIN adaptor. Temperature probe. 250 mL Conical flask. 500 mL beaker to use as a water bath. heating apparatus. ie: bunsen, tripod and gauze mat OR an electric hotplate. Procedure 1. Insert the temperature probe and pressure probe into the spare opening in the twoholed stopper supplied. Ensure that both are firmly sealed and check the stopper for any small cracks, if it is damaged it will need to be replaced. 2. Insert the stopper with probes into the conical flask. It is the air sample in the flask which will be monitored during the experiment. 3. Fill the beaker to about one third, it should not overflow when the conical flask is placed in it. 4. Place the conical flask in the beaker and secure with a clamp (as shown in photo). 5. Run the GETDATA2 program and enter the settings indicated. Page 1 of 3 Chemistry Investigation 5 The Constant Volume Law 6. Start the program and choose a real time plot with scales y-min of 100, y-max of 200, x-min of 10 and x-max of 80. Once sampling begins, immediately start the heat source. 7. When the program has finished sampling you should have a plot illustrating how the pressure of a gas varies with temperature. What does the shape tell you? Processing of Results When the data logging has finished, enter the STAT mode in your calculator and produce a scatter graph of your data, then find the equation of the function that best approximates your data. Use the draw function to see how well the function fits the data. You may wish to use a pc-link cable to transfer screen dumps of your graphs and functions for later analysis. Questions 1. What did the graph of pressure against temperature tell you about the relationship between the two quantities? 2. What function did you find best approximated the data? 3. Write your equation in terms of P and T. 4. Use your equation to predict the pressure of the gas in the conical flask if the temperature was increased to 200ºC. 5. Use your equation to find the volume of the gas when the temperature is zero. 6. How does your equation compare to the Constant Volume Law? Explain why they differ. 7. Relate your results from this investigation to the Kinetic Theory. 8. Describe one consequence of this investigation in the real world. 9. Why do you think the flask wasn't heated more quickly by plunging it into boiling water? 10. Make a list of the errors in this experiment. Extensions Use your recorded data to find the value of absolute zero. Carry out your investigation several more times and average your findings. How does your result compare to the accepted value? Page 2 of 3 Chemistry Investigation 5 The Constant Volume Law Teacher Notes Typical Data The figures here represent the results for the settings listed in the body of the investigation. As you can see, the results are pleasing and the straight-line function produced very closely matched the data. The data clearly indicated a linear relationship between temperature and pressure Comments As you can see this data produced an equation of P = 0.696 t + 90.28 According to this equation, 0 K is -129ºC. This is substantially different to -273 K !! We presume that the temperature probe was lagging behind the pressure probe (due to its heat capacity). Also the temperature probe was measuring the temperature at the bottom of the flask, where the air was possibly cooler. All of these points make for a great postinvestigation discussion. In practice, the only way to get good results is to allow the flask to heat very slowly. This is because the pressure sensor responds much more quickly than the temperature sensor. If a quick response temperature probe was used, ie: one that isn't imbedded in metal, the results would be more accurate. Page 3 of 3 Physics Investigation 1 Conduction of heat Student Outcomes ♦ Explain that heat is the flow of energy from one object to another because of a difference in temperature. ♦ Explain the ways by which heat is transferred: conduction, convection and radiation. ♦ Describe experimental evidence which supports the kinetic theory. ♦ Comprehend and communicate scientific information relevant to the contextual and central ideas. Background Heat transfers through solids by the process known as conduction. Conduction involves the transfer of kinetic energy through the solid, as excited particles collide with each other. As a solid heats by conduction, the average kinetic energy of the particles increase and therefore the temperature increases. Different solids conduct heat to different extents. In this experiment you will compare the relative thermal conductivity of steel and copper. You will use two temperature sensors attached to the ends of metal samples to monitor how the temperature varies as heat moves along each metal. Equipment • • • • • • • • • Casio EA-100 Data Analyzer Casio CFX9850 graphics calculator with GET DATA loaded Two temperature probes as supplied with the EA-100 unit Steel rod and copper rod of identical size (app 10 cm long) Bunsen burner Heat-proof mat Tape Retort stand and clamp Matches Page 1 of 3 Physics Investigation 1 Conduction of heat Procedure 1. Connect the temperature probes to CH1 and CH2 on the data analyzer. 2. Using a link cable, connect the data analyzer to your graphic calculator. 3. Tape the sensor on CH1 to the end of the piece of steel and the sensor on CH2 to end of the piece of copper. 4. Clamp both pieces of metal so that the free ends are 5 cm above the top of the bunsen as in the picture. To ensure that the experiment is fair, make sure that the position of each rod relative to the bunsen is identical. 5. Start the GET DATA program on your calculator, choosing 150 samples at 5 second intervals. The program will record data for the next 12.5 minutes. 6. Quickly light the bunsen burner and set it to the hottest flame (blue). 7. When data collection has finished, turn off the bunsen burner. Processing of Results 1. Graph your results with time (list 1) on the horizontal axis and temperature (list 2 and list 3) on the vertical axis so that there are two heating curves on your graph. 2. This investigation provided two lines on your results graph. Explain the significance of each line. 3. How did the initial and final temperatures of each sample compare? 4. Which sample reached its final temperature first? What does this say about its thermal conductivity? Questions 1. Many high quality saucepans have thick bases. Explain the reasoning behind this and suggest whether steel or copper would be the best material to use. 2. At the kinetic level what do the results tell you about the strength of the bonds between the particles in steel compared to those in copper? 3. Describe any difficulties that you may have experienced while carrying out the investigation and suggest some appropriate improvements. Extensions Plan and carry out an investigation which compares the rate with which radiant heat is absorbed by white cars compared with black cars. Make an appropriate recommendation on the choice of car colour for Australian Car Designers. Page 2 of 3 Physics Investigation 1 Conduction of heat Teacher notes and sample data Typical Data We produced these results over 12 minutes by taking 150 samples at 5 second intervals. The initial temperature was 28ºC and the final temperature for the steel was 70ºC and copper was 85ºC. Comments At first we applied the heat source too far from the probes (our metal samples were rather long). We'd suggest that heat should be applied about 5 cm from the probes. Stress the importance of keeping the leads away from the flame. Presumably, if left for an extended period of time, both pieces would attain the same temperature - suggest that the students investigate this further. Page 3 of 3 Physics Investigation 2 The solar cell Student Outcomes ♦ Connect components in simple circuits and measure values of current and potential difference using ammeters and voltmeters. ♦ Identify the sources of electrical energy in simple circuits. ♦ Identify energy transformations which occur in electrical devices. ♦ Demonstrate familiarity with and safely conduct experimental activities related to contextual applications. ♦ Perform experiments to obtain data so that physical relationships can be formulated or tested. ♦ Present and interpret experimental data in tabular and graphical form. Background A solar cell is a device that converts light energy into electrical energy. In this experiment, you will investigate how the intensity of the incident light affects the voltage output of the cell. Equipment • • • • • • • • • Casio EA-100 Data Analyzer Casio CFX9850 graphics calculator with GET DATA loaded Voltage probes as supplied with the EA-100 unit Light probe as supplied with the EA-100 unit One small solar cell - available from Dick Smith ( ½ W is fine) Light source. eg: microscope lamp or light box Leads Metre rule Retort stand with two boss-heads and two clamps Procedure 1. Connect the voltage probe to the solar cell and plug the probe into CH1 on the data analyzer. 2. Plug the light probe into CH2 on the data analyzer. 3. Using the two clamps, clamp the solar cell and light probe so that they are flush with each other and the cell is vertical. 4. Switch off the lights and darken the room as much as possible. 5. Start the GET DATA program and select 50 samples at 0.1 second intervals. This will give 5 seconds of data logging time. 6. While the data is being collected, move the light source from a distance of a few cm to about 1 m from the cell. Do this smoothly over the 5 seconds. Page 1 of 5 Physics Investigation 2 The solar cell Processing of Results Use your graphic calculator to plot a graph of voltage output against light intensity. What do you notice about the graph? It has been proposed that there is a power relationship between voltage and intensity. ie: V = aI b Where V is voltage, I is intensity and a and b are constants. Use your calculator to find a function of the above form which matches your data. Record your values for a and b and write down the equation. What was the correlation for this equation? Now that you have an equation for the relationship, manipulate your data and produce a straight line graph. What is the significance of the slope of this line? Use a PC link cable to transfer your graphs to a PC so they can be printed and included in your lab report. Questions 1. Are your results sufficient to form a definite conclusion about the relationship between light and voltage? Explain. 2. Try to find an equation of a different form that matches the data. Eg: logarithmic, exponential, trigonometric etc. 3. Assuming that there are several equations that approximate the data, was does this indicate about this sort of experiment? 4. Is the speed with which you move the light source a significant factor in this investigation? Explain your answer. Extensions Solar cells are used in many everyday situations to provide an inexpensive and environmentally friendly source of electricity. For example many isolated stations in Australia's North West use solar cells and vast rechargeable batteries for their energy needs. In practice the power output of a solar cell varies throughout the day. Plan and carry out an experiment that compares the output of a solar cell for various times of the day. You could model a typical day in the lab over a short period of time, or collect your data outside for the course of a day. Write a brief report on your findings and try to explain them. Page 2 of 5 Physics Investigation 2 The solar cell Teacher notes and sample data Typical Data We collected our data over 5 seconds by collecting 50 samples at 0.1 second intervals. This graph shows how the light intensity varied against time when we performed the experiment. Note that there is a maximum and minimum intensity that can be logged, so it is important to stay within these boundaries to collect a good range of data in the 5 seconds. This graph shows a plot of voltage output against light intensity. Note that there is a clear, non-linear relationship between the two. We used the built in regression routines of the graphics calculator to get this relationship and expect that your students would do likewise (ie: we are by no means confident that this is a law of Physics!!). As you can see, our relationship was: V = (0.175 )I (0.149) This graph shows how the above function fits the data. It did so with a correlation of 0.99. We did find several other functions with correlations of > 0.8. Page 3 of 5 Physics Investigation 2 The solar cell Note The specifications for performing this experiment depend on the strength of the light source used. We used a standard microscope lamp, but a light box would work equally well. If students were to use a desk lamp, the maximum and minimum distances may need to be increased to keep within the limits of the data analyzer. This experiment gives students valuable practice in data manipulation, and allows them to further utilize the capabilities of their graphic calculators. Page 4 of 5 Physics Investigation 3 The speed of sound Student Outcomes ♦ Describe and explain the audio phenomena of sound delays. ♦ Design and conduct an experimental activity to verify the speed of sound. ♦ Develop practical skills including the estimation of uncertainty in experimental measurements and the recording and analysis of data. Background In this investigation you will carry out an experiment to verify the speed of sound. Sound is a longditudinal mechanical wave motion. It can be produced by any vibrating body which transfers its energy of oscillation to the air around it. The wave energy propogates as a series of small pressure variations called compressions and rarefactions. The electret microphone detects these pressure changes and they are reflected in the fluctuating voltage output by the microphone, which in turn is captured by the EA-100 data logging unit. Louder sounds create larger pressure variations and thus larger voltage changes in the microphone. By starting data logging at the instant a loud sound is made close to the microphone it is possible to detect an echo of the sound off a distant wall. The time between original and echo can then be read from the data and knowing the distance to the wall, an estimate for the speed of sound can be made. The speed of sound in air at 15°C is 340 m/s. Equipment • • • • • Casio EA100 data analyzer and Casio CFX9850G calculator with program GETDATA2 loaded. Sound probe for the EA-100 Data Analyser (Microphone for CBL). Retort stand and clamp. 10m tape measure. Two large wooden blocks (approx 10 by 10 by 20cm). Procedure 1. Find a solid wall at least 2m tall in a fairly wide open place (there should be no other large objects in the vicinity which could reflect sound back to the microphone). A lawn up to the wall is preferable to paving or other hard surface which can add to reflected ‘noise’. 2. Clamp the microphone into the retort stand about 50cm off the ground and point the it towards the wall, which should be 4 to 8m away. 3. Measure the exact distance of the microphone to the wall using the tape measure. 4. Connect the CBL microphone to the EA-100 unit using the CH3 socket. 5. Using a link-cable connect the EA-100 to your graphic calculator. Page 1 of 4 Physics Investigation 3 The speed of sound 6. Start the GETDATA2 program and set up sampling as shown. Make sure you use both the custom calibrate and trigger options. 7. For the custom calibration equation, always set a = 1, but for b, put the EA-100 unit into multimeter mode, view CH3 (use CH-View), and use the average value which the microphone is returning, but make it negative. This has the effect of centering the microphone signal to 0V so that we can use a trigger threshold of 0.25V to trigger data sampling. 8. For the trigger value, set exactly as shown. If the microphone triggers too early when carrying out the experiment, set this a bit higher than 0.25. 9. When set up is complete, choose Go to initialise the EA100 for sampling. 10. When ready to clap the wooden blocks together, press Go again, which should put the EA-100 unit into the ‘READY’ state, waiting for a trigger. 11. Holding the blocks close to the microphone, clap them together firmly and cleanly. Triggering should occur and ‘DONE’ will appear on the EA-100 screen. If the EA-100 remains in ‘ready’ mode, bang the blocks together harder! If still nothing happens, choose the calculator Halt option and re-check sampling set up, trying a smaller trigger value. 12. Once EA-100 shows ‘DONE’, press F1 to download data into the calculator, choose No to rounding and then choose a Line graph. If your graph shows an initial peak (banging the blocks together), followed by another obvious peak further along the plot (the echo off the wall), continue to processing of results. If not, repeat steps 9 to 12. An example of a suitable plot is shown. Processing of Results Use the cursor keys (SHIFT F1 first) to trace along the graph, recording the time at which the two major peaks occurred (x values). Subtract these to find the time the sound took to travel from the microphone to the wall and back again. Divide the distance the sound travelled (to the wall and back again) by the time taken to arrive at the speed of sound. If you have a pc link cable, save a copy of the screen to a PC for inclusion in your report. Page 2 of 4 Physics Investigation 3 The speed of sound Questions 1. Compare your calculated value with the accepted value for the speed of sound. Comment on how well they agree. 2. Would performing the experiment several times and averaging the values give a better result? 3. When they are clapped together, does the distance of the wooden blocks from the microphone, and their position relative to the wall, make any difference? 4. What changes would you expect if the microphone was placed further from the wall? Closer to the wall? 5. The EA-100 unit samples at one reading every 0.001s. Do you think this is sufficiently often to capture the peaks at the exact moment they occurred? 6. Why was triggering necessary in this experiment? 7. Summarise all the possible sources of error in this experiment. Extensions Investigate differences produced by setting the microphone at different distances from the wall. Examine the initial burst of sound when the wooden blocks are brought together. Can you suggest changes to the trigger threshold or falling/rising trigger condition to improve accuracy? Does using a falling trigger, through a negative value for the trigger threshold, make any difference to your results? The procedure outlined above used the time difference between peak values to determine the speed of sound. Is there any difference if minimum values are used instead? Page 3 of 4 Physics Investigation 3 The speed of sound Teacher notes and sample data Typical Results This experiment was carried out by students on a lawn, 5m away from a 1.8m high brick wall. Distance = 2 x 5 = 10m Time = 0.033078 - 0.001744 = 0.031334s Speed = 10 ÷ 0.031334 = 319m/s Comments The set up process may seem a bit involved at first sight, but in practice is accomplished very quickly. Students seem to enjoy the use of a trigger to initiate sampling, and this is an easy experiment for them to learn and understand the process. The sampling rate of 0.001s makes it difficult to always capture peaks, so it is often necessary to repeat the experiment several times before a good graph is obtained. The Vernier microphone returns a voltage in the range 0 to 5V, centered on about 2.5V. The actual centered voltage depends on the condition of the EA-100 batteries. If using an external 6V power supply, it can be as high as 2.7V, or if the batteries are low, down to 2.4V. Hence care needs to be taken to set up a successful trigger value. The steps outlined in procedures 7 and 8 usually produce good triggering. The screens above show that the maximum displacement of the centered voltage is only about ±0.6V. Close examination of the initial sound burst usually shows a decrease in displacement, and so students may try setting their own trigger conditions taking this into account. Page 4 of 4 Physics Investigation 4 Sound Waves Student Outcomes ♦ Define the terms amplitude, frequency and wavelength of a wave. ♦ Produce graphs of displacement v time for sound waves and relate the features of such graphs to the properties of the sound waves. Background Sound is a longitudinal wave, however; when a wave is captured electronically, we can represent it as a 2-dimensional wave. In this investigation you will capture a series of sound waves and analyse them graphically. Equipment • • • • Casio EA-100 Data Analyser. Casio CFX9850 graphics calculator with GETDATA2 program loaded. Sound probe for the EA-100 Data Analyser (Microphone for CBL). Audio signal generator with speaker. Procedure 1. 2. 3. 4. 5. 6. 7. 8. Plug in the signal generator and connect it to the speaker. Connect the CBL microphone to the EA-100 unit. Using a link-cable connect the EA-100 to your graphic calculator. Start the GETDATA2 program and set up sampling as shown. Set the frequency on the signal generator to about 80 Hz and switch it on. Adjust the volume to an audible level. Ensure that the waveform is sinusoidal if there is a choice of waveforms. Hold the microphone about 3 cm from the speaker and start collecting data. The program will now allow you to graph the data. Choose no rounding and a line graph. The resulting graph represents the captured sound wave. You may wish to use a pc link cable to capture a screen dump of this graph to be included in your report of this investigation. Repeat steps 5 - 7 for sound waves of slightly higher frequency. eg: 100 Hz. Page 1 of 3 Physics Investigation 4 Sound Waves Processing of Results Compare the sound waves that you have captured and describe the main differences between the graphs produced. Questions 1. Compare the number of waves displayed for the sound signals that you captured. 2. How did raising the frequency of the sound affect the graph produced? 3. How does the distance between the peaks on the waves relate to the frequency? What is this a measure of? 4. Given that the speed of sound is 330 ms-1, calculate the wavelength of each of the waves that you captured. Why is the wavelength not represented on your graphs? Extensions Investigate how changing the loudness of the sound affects the graphs produced. You will need to investigate this in STAT mode, as the graph produced in the GETDATA2 program automatically scales the y-axis. ie: you will have to plot and analyse the data in list 1 and 2 directly. The audio signal generator probably has a choice of possible waveforms (eg: saw-tooth and step function). Repeat the experiment for some of these and explain your results. Investigate the concept of beats by adding the data produced by two slightly different frequencies and plotting the result. Page 2 of 3 Physics Investigation 4 Sound Waves Teacher Notes Typical Data The data shown here was collected using the settings described in the investigation. The first graph is for a frequency of about 80 Hz. The second graph is for a frequency of about 120 Hz. Comments This investigation is limited by the sampling rate of the EA-100. The maximum sampling rate is every 0.001 s. For a 100 Hz wave, this gives 10 data points per wave, and therefore a generally smooth curve. If the frequency is too high the number of data points per wave becomes too few and the graph is less accurate. This is illustrated by the second wave above. If you want to capture sound waves of a much higher frequency, you should consider using sound analysis software that is available for personal computers. Page 3 of 3 Biology Investigation 1 Energy release by yeast during the breakdown of carbohydrate. Student Outcomes ♦ Observe phenomena and describe, measure and record these as data. ♦ Identify and explain the importance of the controlled and experimental variables in scientific investigations. ♦ Analyse and draw conclusions from simple data. ♦ Investigate the actions of enzymes and define their functions. Background In the process of breaking down carbohydrate, yeasts release a certain amount of energy. This experiment sets out to investigate the amount of energy released through monitoring the temperature of a solution of sugar in water to which dried bakers yeast has been added. Equipment • • • • • • Casio EA-100 Data Analyzer. 1 or 2 temperature probes as supplied with EA-100 unit. SB-62 cable as supplied with EA-100 unit to link EA-100 to calculator. Casio CFX9850 graphics calculator with GET DATA program loaded. 1 or 2 similar vacuum flasks or other well insulated vessels, depending on the number of temperature probes available. The second, if available, to be used for experimental control. Water, sugar and a sachet of dry bakers yeast or a slice of compressed yeast. Procedure 1. Thoroughly clean the flasks. 2. Add 20g of sugar to 400ml of water, stir until dissolved and allow to settle to room temperature. 3. Divide the sugar solution equally between the vacuum flasks and place them in a draught free place not subject to large temperature changes. 4. Add about 7g of dried yeast or 15g of compressed yeast to one of the flasks and stir well. 5. Insert one temperature probe into the sugar/yeast solution and the other into the plain sugar solution. 6. Start the GET DATA program on your calculator, choosing 120 samples at 300 second (5 minute) intervals. The program will record data for about ten hours. 7. Once sampling has begun it is possible to turn off and disconnect the calculator from the EA-100 Data Analyzer to conserve battery life. 8. Once data sampling is complete re-connect the calculator to the EA_100 unit and run the GET DATA program again to download sampled data. Page 1 of 3 Biology Investigation 1 Energy release by yeast during the breakdown of carbohydrate. Processing of Results Graph your results with time (List 1) on the horizontal axis and temperatures of both probes on the vertical axis. Trace along your graph to determine the temperature rise of the solution due to the energy release by the yeast. If you used a control flask, eliminate the effect of ambient temperature changes by subtracting the control temperatures from the yeast/sugar solution temperatures as shown. Then replot time (List 1) v temperature increase (List 4). Questions 1. 2. 3. 4. 5. 6. Sketch a copy of your graph in your notes and label the various points of interest. Explain how you determined the rise in temperature caused by the yeast. Why do you think the graph has the shape that it does? What caused the temperature to rise and how long did it rise for? What caused the temperature to fall and how long did it fall for? What do you think would happen if you added (i) more sugar (ii) more yeast at the start? 7. Research the chemical equation for breakdown of carbohydrate by yeast. What are the products of this breakdown? What do they depend upon? Extensions Design an experiment to check your predictions to Q6. The energy release process is different depending on the presence or absence of oxygen. Design an experiment in which you could investigate the effect of the presence or absence of oxygen on the energy released. Page 2 of 3 Biology Investigation 1 Energy release by yeast during the breakdown of carbohydrate. Teacher notes and sample data Typical Results The graph shown was obtained by taking 120 samples at 5 minute (300 second) intervals, taking a total of about ten hours. The initial temperature was just over 26°, peaking just under 30°C after 3 hours and then returning to 26°. The control temperature climbed fairly steadily over this time by about 0.5°C. To eliminate this factor subtract the control temperatures from the culture temperatures and store the results in List 4. (This operation carried out in RUN mode shown right. To obtain List press OPTN, F1, F1). Then graph List 1 (Time) against List 4 (temperature rise). Comments 7g sachets of dried bakers yeast are easily obtained from most supermarkets. The normal course of energy release by aerobic organisms can be summed up as carbohydrate (monosaccharide sugar) → pyruvic acid → carbon dioxide + water + 2870kJ. Only the breakdown of pyruvic acid necessitates the use of oxygen. In the absence of oxygen, yeasts can bring about the breakdown of carbohydrate as follows sugar → pyruvic acid → carbon dioxide + ethyl alcohol + 1090kJ. Page 3 of 3 Biology Investigation 2 Respiration of carbon dioxide Student Outcomes ♦ Demonstrate competence in the process skills of science associated with designing and performing controlled experiments, collecting, recording, presenting and interpreting data. ♦ Explain how the respiratory system is adapted for efficient uptake of oxygen and release of carbon dioxide. ♦ Describe how the circulatory system transports nutrients and oxygen to cells and waste material and carbon dioxide from the cells. ♦ Describe the composition of inhaled and exhaled air. Background The trillions of cells making up the body require a continuous supply of oxygen to carry out their vital functions. As cells use oxygen, they give off carbon dioxide, a waste product the body must get rid of. Normally active body cells produce about 200mL of carbon dioxide each minute – exactly the amount excreted by the lungs. In this investigation you will confirm that the body exhales carbon dioxide and that exercise is a factor in the amount of carbon dioxide produced. This can be done by observing the pH of water as expired air is blown through it. When carbon dioxide dissolves in water, carbonic acid is produced which leads to a decrease in the pH of the solution. CO2 + H2O → H2CO3 Equipment • • • • • • Casio EA100 data analyzer and Casio CFX9850G calculator with program GETPULSE loaded. Vernier pH System (PH-DIN) and CBL-DIN adaptor. Copy of notes ‘Using the GETPH program’ Small conical flask (250mL) Drinking straw Tap water Page 1 of 4 Biology Investigation 2 Respiration of carbon dioxide Procedure 1. Read the notes on using the GETPH program and familiarise yourself with how to monitor pH using the data logger and calculator. 2. Choose a member of your group to act as the test subject. That person should sit down and be allowed to rest to minimise the amount of exhaled carbon dioxide. 3. Fill the conical flask with 100mL of water and place into the water a straw and the pH probe. Make sure that the tip of the probe is fully immersed under the water. 4. Connect the pH probe to CH1 on the data analyser. 5. Using a link cable, connect the data analyser to your graphic calculator and start the GETPH program. 6. Set up sampling as shown in the screen. 7. Choose Go and wait until a steady reading is shown on the calculator screen. Waiting is necessary to allow the pH probe and amplifier to reach equilibrium before the experiment is started. This can take over one minute. Then choose Go again to start sampling. 8. Wait for a few points to be plotted and then the test subject should start to exhale air slowly and continuously through the straw into the water until sampling finishes. It will be necessary to take several breaths to achieve this, but try and keep the time between breaths to a minimum. 9. Make a copy of the resulting graph in your notes as accurately as you can, or use a pc link cable to save the screen to a PC. 10. To determine the starting and finishing pH values, press EXE to return to the main menu and choose the Grph option, which will re-scale and re-plot the graph. Trace along the graph using the arrow keys (SHIFT F1 first). 11. Move to the point where the pH begins to drop and note both pH and the time. Then complete a table to record the pH at 10 second intervals: Time (seconds) After rest pH After exercise pH 0 10 20 30 40 50 60 70 80 90 12. Now have the test subject undertake some vigorous exercise such as running up and down stairs for several minutes. 13. Whilst the test subject is exercising, prepare a fresh flask of water. 14. Now repeat steps 7 to 12. Page 2 of 4 Biology Investigation 2 Respiration of carbon dioxide Processing of Results Use the table of values above to make a two line graphs on one set of axes of pH against time. Note on each line the starting pH, finishing pH and change in pH. If further analysis of the data is required, Exit the program and change to STAT mode. Time is in List 1 and pH in List 2 of your last sample. Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. Explain how the pH changed with time for the first ‘after rest’ sample. What was the total change in pH? Does this change indicate the water becoming more acidic or more alkaline? Why did the pH change? Compare how the pH changed between the ‘after rest’ and ‘after exercise’ samples. What where the similarities? What where the differences? What effect does exercise have on the amount of carbon dioxide exhaled? What do you think would happen if you repeated the investigation with a different test subject? What problems did you encounter with sampling? What could you do to overcome these problems? Extensions Investigate what happens if you continue blowing exhaled air through the water for an extended time. Does rest or exercise influence the results of extended blowing? Consider what substances you could blow through the water to reverse the change in pH. How could you test your ideas? Page 3 of 4 Biology Investigation 2 Respiration of carbon dioxide Teacher notes and sample data Typical Results Here is a typical graph produced for the resting pH levels. Students may extend the number of samples to 200 to investigate whether the pH actually decreases any further. For this water the pH started at about 7.4 and decreased to 6.3. The same sample after re-plotting with the Grph option so that tracing is possible. After leaving the program and switching to STAT mode, the last sample can be explored (time in List 1 and pH in List 2). Comments Most tap water will produce results similar to those above, although the initial and final values are likely to differ from area to area. As a result some small changes to the Y-Scale may be needed in the initial set-up. Watch out for over vigorous blowing resulting in water spilling all over the EA-100 unit and calculator. It pays to keep the hardware fairly distant from the test subject, even though the students like to watch their graph evolve as they blow. Also, it can’t be stressed enough that the waiting time before the sampling is begun is usually at least one minute – the time taken for the pH amplifier to settle down. Page 4 of 4 Biology Investigation 3 Effect of exercise on heart rate Student Outcomes ♦ Demonstrate competence in the process skills of science associated with designing and performing controlled experiments, collecting, recording, presenting and interpreting data. ♦ Explain the regulation of cardiac output to supply the demands of active muscle cells. ♦ Describe the major cardiovascular and respiratory diseases and explain the factors that increase their risk of occurrence. ♦ Accurately measure time and pulse rate. ♦ Develop a positive attitude towards the differences in physical capabilities among individuals and towards the maintenance of personal health and a commitment to the adoption of a health-sustaining lifestyle. Background The normal adult blood volume is about 5L. Using the normal resting values for heart rate (75 beats per minute) and stroke volume (70mL per beat), it can be calculated that the entire blood supply passes through each side of the heart once each minute. Exercise raises heart rate, as increased circulation is needed to meet the demands of transport of oxygen and carbon dioxide to and from cells. As soon as exercise stops, the heart immediately slows down. The time taken for the heart rate to return to the resting value is a good indicator of physical fitness. In this investigation you will select a sample of students of varying degrees of fitness and measure typical increases in heart rate due to exercise and also compare recovery heart rates. Equipment • • • • Casio EA100 data analyzer and Casio CFX9850G calculator with program GETPULSE loaded. Vernier heart rate monitor (HRM-DIN) and CBL-DIN adaptor. Copy of notes ‘Using the GETPULSE program’. An aerobics type ‘step box’, or access to a step at the bottom of a staircase for use during exercise. Page 1 of 4 Biology Investigation 3 Effect of exercise on heart rate Procedure 1. Read the notes on using the GETPULSE program and familiarise yourself with how to monitor pulse rates using the data logger and calculator. 2. Choose a sample of 3 students of differing fitness levels, the wider the range the better. For each of the three in turn: 3. Connect hardware together and start the GETPULSE program. 4. Measure (and record in a copy of the table below) the resting heart rate after 5 minutes of inactivity. 5. Spend 3 minutes performing step-ups. Keep GETPULSE running during this time, but the heart rate monitor is not designed to collect heart rates during exercise. 6. Immediately the 3 minutes is over, note the next heart rate, record in the table in the maximum column, record the rate after 1 minute in the recovery column and then record rates at 1 minute intervals until it returns to the resting value. It may be necessary to extend the table. Note that GETDATA calculates heart rates at 15 second intervals, so record every fourth reading. Name Resting Maximum t=0 Recovery t=1 2 3 4 5 6 7 Processing of Results Before continuing with this investigation is important to examine your data for any unusual values. You will have seen that the heart rates measured by GETPULSE are subject to some minor fluctuations. Unusual readings can often be corrected by examining heart rates either side of suspect values and using these to interpolate. Heart rates are stored in List 4 of your calculator, with their time of recording (in minutes) in List 3. On the same axes, draw a graph to show the heart rates of the three students. You can do this on your calculator by going to STAT mode, clearing any existing data and entering the times 0, 1, 2, 3, …. in List 1, and the heart rates in Lists 2, 3 and 4. Set up each graph as shown in the screen shot (choose a different colour for each line) and use SEL to select all 3 graphs before drawing. For each student, calculate: • The difference between resting and maximum heart rates • The difference between the maximum and recovery heart rates. • The time taken to return to resting heart rate from the end of exercise. Page 2 of 4 Biology Investigation 3 Effect of exercise on heart rate Questions 1. Compare and contrast the shapes of the three lines on your graph. 2. How does the difference between the resting and maximum heart rate relate to the fitness of each student? Is this what you would expect? Why? 3. How does the difference between the maximum and recovery heart rate relate to the fitness of each student? Is this what you would expect? Why? 4. How does the time taken to return to resting heart rate relate to the fitness of each student? Is this what you would expect? Why? Extensions By carefully screening the fitness of a selected range of students and determining for each the difference in maximum and recovery heart rates (ie the drop in heart rate over the first minute after exercise) try to decide on a suitable range of differences which indicate (i) a poor level of fitness (ii) an average level of fitness, and (iii) a high level of fitness. Page 3 of 4 Biology Investigation 3 Effect of exercise on heart rate Teacher notes and sample data Typical Results The graph shown was collected over a period of 10 minutes, during which time 6 readings were rejected. The 3 phases of the investigation are clearly visible, with a level resting pulse, a rapid increase up to about 140bpm during exercise and then gradual recovery to resting after exercise. GETPULSE was started about 1 minute before the student began to exercise, and the last heart rate recorded before exercise was 71. The maximum rate at the end of exercise was 138, and after 1 minute, the recovery heart rate was 105. The total time for heart rate to return to the original resting rate was just over 6 minutes. This last figure is a bit speculative, as the next reading from the monitor gave a heart rate of 76. Comments The heart rate monitor can be a frustrating probe to work with. For some students the results returned are excellent, yet for others, no amount of moving and fiddling around seems to produce sensible readings. In general, the placing the clip on the ear lobe produces best results, although other folds of skin can be tried, including between the thumb and forefinger. The Vernier heart rate monitor is not designed for collection of data during exercise, although some success has been observed with particular students. Hence this investigation does not include data collection over the entire length of the rest - exercise rest cycle. The resting to maximum change in heart rate is not a good indicator of fitness, but simply reflects the effort put into exercise by the students. Maximum to recovery, the drop in heart rate over the first minute after exercise, is an excellent guide to fitness, and studies have shown that a drop of less than 30 beats per minute indicates poor health, whilst a drop of more than 50 beats per minute indicates excellent shape. The time to return to resting is similarly a good indicator of fitness, though less commonly used than recovery rate. The shorter, the fitter the individual. Page 4 of 4 Biology Investigation 4 Difference of average heart rates between males and females Student Outcomes ♦ Demonstrate competence in the process skills of science associated with designing and performing controlled experiments, collecting, recording, presenting and interpreting data. ♦ Explain how genetic and environmental factors influence all aspects of human development and senescence. ♦ Discuss the structural and physiological changes that occur during human development and senescence. ♦ Develop a positive attitude towards the differences in physical capabilities among individuals. ♦ Accurately measure time and pulse rate. Background Known factors that influence heart rate include exercise, body temperature, age and gender. For example, resting heart rate is fastest in the foetus (between 140 and 160 beats/minute) and gradually declines throughout life. In this investigation the effect of gender on resting heart rate for a small sample of students will be investigated. Equipment • • • Casio EA100 data analyzer and Casio CFX9850G calculator with program GETPULSE loaded. Vernier heart rate monitor (HRM-DIN) and CBL-DIN adaptor. Copy of notes ‘Using the GETPULSE program’ Procedure 1. Read the notes on using the GETPULSE program and familiarise yourself with how to monitor pulse rates using the data logger and calculator. 2. Plan how you will choose your sample of students, being careful to make sure it is unbiased and then plan how you will collect data to ensure you are measuring resting heart rate. (It will not be necessary to start and stop the EA-100 as you move from one student to the next. One method to use is once you have a couple of consistent readings for a subject, write it down, move the ear clip to the next person, wait for a steady reading, and so on.) When you have checked your plan with your teacher, collect the data. Page 1 of 3 Biology Investigation 4 Difference of average heart rates between males and females Processing of Results Using the STAT mode of your calculator, enter all the heart rates recorded into List 1, set up Gph1 as a histogram for the data in List 1, and DRAW. Comment on the spread of all heart rates and copy the histogram into your notes (or use a pc link cable to save a copy of the screen to a computer). Whilst viewing the histogram, choose 1VAR (F1) to see the summary statistics for your whole sample and record the mean. Next enter all the boys heart rates into List 2 and the girls into List 3 and set up GPH2 and GPH3 as boxplots (See screen at right for SET example) Then use SEL to draw graphs 2 and 3 simultaneously (See example screen at right). Any differences in the heart rates for the boys and girls should be apparent from the two boxplots. Make a copy of them in your notes. Choose 1VAR to see the summary statistics for each group, recording the mean. Trace along the graphs (SHIFT F1 together with arrow keys) to explore their key points. Summarise your findings from this investigation in your notes. Questions 1. What do your results tell you about the effect of gender on resting heart rate? 2. Do your results agree with those for the population as a whole? Try to explain any differences. 3. What do you think would happen if you repeated the investigation with a different sample of students? 4. What steps did you take to make sure your sample was unbiased? 5. What steps did you take to ensure you measured resting heart rate? 6. What problems did you encounter with data collection? 7. How could your results be used to indicate whether a person has an abnormally low or high pulse rate, taking into account their gender? Extensions Design an experiment to consider other effects on resting heart rate, such as age, fitness or temperature. Also consider how these factors may have influenced the data collected in the initial investigation of gender differences on resting heart rate, and re-design the experiment to control these factors. Page 2 of 3 Biology Investigation 4 Difference of average heart rates between males and females Teacher notes and sample data Typical Results The data shown was collected fairly randomly from a mixed group of 14-year-old students consisting of 15 boys and 15 girls. The boys (blue) had an average pulse rate of 68 whilst the girls was significantly higher at 76. The boxplots nicely illustrate this. The histogram was for all 30 students, showing the distribution of pulses for the group. Some students may have the statistical knowledge to test whether the difference is statistically significant using a test for the difference of two means. Comments Statistics from large random samples show that average heart rate is faster in females (72 to 80 beats/minute) than in males (64 to 72 beats/minute). If extensions are investigated, the following should be observed: • • Fitness. The resting heart rate in the physically fit tends to be substantially lower than those who are out of condition. In trained athletes, it may be as slow as 40 to 60 beats/minute. Temperature. Heat increases resting heart rate by enhancing the metabolic rate of cardiac cells. Cold has the opposite effect. It directly decreases heart rate. Page 3 of 3