In this project you will use the Vernier Multi-purpose Laboratory Interface (MPLI) to perform one experiment. No lab report is due, but you will be requested to exhibit your setup and submit to a demonstration interview. You should be prepared to answer "how to" questions from the procedures sections of the outlines below, but you need not do the actual written work. Choose your experiment from among those below:
Pasco's LabNet Geiger Interface
A. INTRODUCTION
Vernier's Precision Timer is a very valuable asset to the physics teacher, especially when kinematics is concerned. The ability to precisely time the swing of a pendulum, the fall of a "picket fence," or determine the motion of a ball on an incline can be instrumental in teaching fundamental physics concepts.
In this project you will use Vernier's Precision Timer program along with several home-built photogates to: 1) determine the acceleration due to gravity, 2) to verify the Newton's second law, F = ma, by comparing theoretical and actual accelerations of masses making up an Atwood's machine, and 3) use an airtrack to verify the conservation of momentum.
Following your introduction to Vernier's Precision Timer program and photogates, complete experiments II and III which are appended. These are two lab exercises from Bradley University which uses Precision Timer extensively in its introductory physics courses.
Clearly, there will be some minor differences between the equipment you use and what Bradley University uses, but this should make no essential difference in your work.
B. PROCEDURE
1. For Bradley Experiment II, follow all instructions. Print out all the graphs and tables for one trial only. In a brief report, compare your results of the acceleration due to gravity with the "accepted value" of 9.80 m/s^2. Determine the % error. Discuss in detail the uncertainties in your result and possible causes.
2. For Bradley Experiment III, follow all instructions. Again, print out all the graphs and tables for three different trials. In a brief report, derive and compare theoretical versus actual accelerations for the known masses and frictional effects. Determine % error for each of three trials. Discuss in detail the uncertainties in your results and possible causes.
3. Using your own ingenuity, set up an air track and conduct an experiment showing conservation of momentum in one of the two following situations: collisions (where two carts stick together) or "explosions" (where two carts are propelled apart). Conduct trials for four different sets of masses. Show and explain your setup to the course instructor.
A. INTRODUCTION
Motion can be a complex phenomenon, especially the motion of a forced, damped harmonic oscillator. In this exercise we will deal with the simpler case of the unforced, "undamped" harmonic oscillator. (The mass of the harmonic oscillator will be large enough and damping from friction small enough so that we can consider this case "undamped.")
We will observe the motion of a weight on a vertically hung spring (assumed to be massless) and examine the relationships between restoring force, displacement, velocity, and acceleration. (The mass of the suspended mass will be large in comparison to the mass of the spring so that a "massless" spring becomes a more realistic approximation.
The student will work through the theory of motion for this system, and then compare the relationships between the aforementioned parameters -- F, x, v = x', and a = x" -- with the theory.
B. PROCEDURE
1. Assume that a mass, m, is suspended on a (massless) vertical spring that has a spring constant k. The mass is displaced from equilibrium position a distance x and set to oscillating up and down. The equation of motion can be written as:
x" = - kx/m
(Where does this come from?) Solve this differential equation for x as a function of t. Write your final solution in a form involving only sine or cosine functions and constants. As necessary, evaluate the constants using boundary conditions of your choosing.
2. Given that v = dx/dt = x', find the theoretical relationship for v.
3. Given that a = d2x/dt2 = x", find the theoretical relationship for a.
4. By Newton's second law we know that F = ma. Write the equation for F and find the theoretical phase relationships between the variables F, x, v, and a.
5. Using Vernier's acoustical motion detector and force transducer, set up your experiment with the force transducer at the top supporting the spring and the motion detector below. (Read the equipment manuals as necessary; see your instructor for their availability.) Plug the acoustical motion detector into the MPLI's channel A. Plug the force detector into the MPLI's channel B. See the set-up diagram at the top of the next page.
Set-up for Apparatus
6. Start the computer and load the motion plotter program. The program is titled "mpx.exe" in the \vernier\mpx directory. Using the options available, turn on channel B and adjust the scaling to fit the expected range of displacements and distances, velocities, accelerations, and forces to be encountered in the oscillating spring setup.
7. Once scaling is set appropriately, vary the parameters as necessary to plot SMOOTH real-time graphs showing force, displacement, velocity, and acceleration as a function of time. Print out this set of graphs and determine the phase relationships between the four variables. Compare this with theory. Attempt to explain any deviations between theory and observation. Consider friction (was the system truly undamped?), the "massless" spring (was it truly massless?) and anything else you consider relevant.
8. Prepare a thorough lab report using an outline you might expect your students to employ.
A. INTRODUCTION
To an unfortunate degree the study of radioactivity in the high school classroom is limited. This stems from several considerations: 1) lack of proper equipment, 2) lack of relatively safe radioactive sources, and 3) fear of ionizing radiation. Many, if not most, physics teachers have had little to no education in the proper care and use of radioactive sources. In this project you will use Pasco's LabNet Geiger Interface (LGI) unit and software in the hopes of overcoming at least some of these limitations. The LGI set-up is designed to be user-friendly and self-explanatory.
B. PROCEDURE
1. Begin this project by reading the Nuclear Safety precautions in Appendix A (page 44) of the LGI handbook. Be certain to abide by these safety precautions at all times.
2. Familiarize yourself with the Geiger/Mueller (G/M) sensing apparatus. Begin by opening the LGI handbook to page 12. Follow the procedures outlined therein. Be certain to read Appendix E about printing data.
3. Using the sealed Cs-137 gamma-ray source provided (no alpha or beta sources will be used in this project), work through the introductory activities listed on pages 22-23.
4. Perform one of the following activities: Random Events Experiment (pgs. 24-25), Half-Life Experiment (pgs. 26-27), or Radiation Shielding Experiment (pgs. 28-29). For the Half-Life Experiment, contact your PHY 302 instructor for a "Minigenerator and watchglass." Create data tables and printed results whenever possible using the Graphical Analysis III program. Prepare a lab report for the project you've chosen employing the same format you would expect your high school students to use.
5. Prepare for the Inverse-Square Law Experiment (pgs. 30-31). Note that before you can start this experiment, you must "calibrate" the G/M tube. (Note the warning to the student on line "a." of the DATA COLLECTION section.) You are the teacher. Calibrate the tube telling your PHY 302 instructor just where the effective center of the G/M tube is. Use your own procedures to determine the calibration letter.
6. Perform the Inverse-Square Law Experiment. Prepare a lab report for the project employing the same format you would expect your high school students to use.
A. INTRODUCTION
Very few high school physics laboratories have workstations outfitted with oscilloscopes. The primary reason for this is because of their relatively high cost and limited usefulness in the introductory physics curriculum. This high cost and limited usefulness can be gotten around, however, by using the desktop computer as an oscilloscope.
Vernier's MultiPurpose Laboratory Interface software is mutli-purpose. One of its modes of operation is that of the oscilloscope. The MPLI's oscilloscope mode can be used to analyze electronic circuits, one example of which is the RC circuit. In this project you will use Vernier's MPLI oscilloscope mode along with a capacitor, resistor, and square-wave signal generator to determine the time constant and half-life of an RC circuit
B. PROCEDURE
1. Begin this project by carefully studying the introduction of the accompanying "lab manual." (The lab outline comes from Bradley University.) You need concern yourself only with that portion of the introduction that deals with the square wave form of applied voltage.
2. Set up the RC circuit as outlined in section II. of the lab manual. Be certain to include connections labeled "input B" or "input C." These circuits will be utilized in the analysis of this circuit.
3. Set up and attach the MPLI oscilloscope as indicated.
4. Follow the outlined procedures for analyzing this circuit through Part II. G of the lab guide.
5. Prepare a thorough lab report following the format you would expect your students to follow when they do their write-ups. Be certain to outline results and show calculations in an analysis sheet.
A. INTRODUCTION
Vernier's supply of scientific probes is a valuable asset to the physics teacher. A variety of scientific probes have been designed to work with the MPLI, the MultiPurpose Laboratory Interface. The MPLI is an analog-to-digital converter. When properly calibrated, the MPLI converts voltages from sensors into units of magnetic field strength, electromotive force, luminosity, temperature, or force, depending upon the probe used.
In this project you will use Vernier's MPLI program along with the direct-connect temperature probe to determine the specific heat of metals and the heat of fusion of water. The temperature probe uses the LM34CH transducer. It produces an output voltage which varies in a linear fashion with temperature. The range of the probe is -15oC to 110oC.
B. PROCEDURE
Before you can use the temperature probe, you must calibrate it. That is, you must "show" the computer how to interpret the output voltage of the temperature probe in a meaningful fashion. Begin by plugging the temperature probe into the "A" DIN connector on the MPLI. Start the MPLI application, selecting mode Z-CALIBRATION from the main menu. Select Z-CALIBRATE INPUT from the second menu. Follow the instructions on the screen when calibrating your temperature probe.
Please note that two water baths are needed for calibration. One bath should be hot water, the other should be cold water. For best results, use temperatures in the range you will be measuring during your experiment. For example, if you are going to measure the temperatures in a room, calibrate at 15oC and 30oC. If you will be working with a wide range of temperatures, you will want to calibrate for a wider range of temperatures, say 0oC and 100oC. Once you have created a calibration file, save it under the name TP#### where the #### refers to the first four letters of your last name. Use Y-SAVE CONFIGURATION to save. Once the file is saved, choose X-EXIT TO MAIN MENU and continue.
Using your calibrated temperature probe, create a real-time graph showing the variation in temperature of the probe when it is plunged from a cold bath to a hot bath. (The axes must be properly labeled with temperature versus time, not voltage versus time.) Print out this graph.
Begin work to determine the specific heat of the metals and the heat of fusion of water. Do so by completing Experiment XVI found appended. Prepare a thorough lab report showing your findings. Use an outline similar to one that you might require your high school students to use.