PHYS1405 – Conceptual Physics I
Kinesthetic Kinematics
Leader: ___________________
Skeptic: ___________________
Recorder: __________________________
Encourager: ________________________
Materials
Laptop with power adapter
LabPro with cable
Motion Detector with cable
C-clamp for motion detector
Introduction
The purpose of this lab is to develop an intuitive understanding of the graphs of position and velocity as a function of time. An important goal is to differentiate between velocity and acceleration. Before starting this lab, review the definitions of velocity and acceleration.
Background Information
Our procedure will be to record the position as a function of time using ourselves as the object of study. We will measure our position as a function of time using the LabPro interface and a sonic motion detector. We will control the interface and detector using a software package called LoggerPro.
The sonic motion detector measures distances by making use of the fact that sound travels at a constant speed through the air. The sonic ranger measures position by emitting a brief pulse of ultrasound (frequency = 40,000 Hz) towards a target and then detecting the sound reflected from the target. The sonic ranger determines the time interval that passes between when the pulse of sound is emitted and the reflected sound returns. The distance is determined from d = v s t r
/2, where v s
is the speed of sound, and t r is the time interval between when the sonic ranger emits a pulse of sound and when it detects the reflected sound. The result is divided by 2 because the time interval represents a round trip for the sound, and is thus double the distance to the target. The speed of sound depends on the temperature, but at room temperature, the speed is approximately 343 m/s.
Procedure
1. Set-up
The experimental set up is shown in figure 1. To set up the apparatus, plug the cable from the motion detector into the socket labeled Dig/Sonic 1 on the LabPro. Verify that the LabPro is plugged into the computer and that it has power. Clamp the motion detector to a chair in a position such that the motion detector has an unobstructed view of you walking towards and away from the detector over a distance of several meters. The motion detector attaches to the clamp via a bushing on the back. Note that the LabPro motion detector will not allow you to measure distances of less than .5 m or greater than about 5 m.

2. Start the Software
LoggerPro controls the equipment with files called experiment files. Follow the instructions given by your instructor to download the experiment file for this equipment to your computer’s desktop. Double click on the experiment file to start LoggerPro.
3. Test the Set-up
To verify that the apparatus is running correctly, we will make a quick graph of position versus time. The monitor should display a blank graph. On the right and above the graph is a small button labeled COLLECT . Click on the collect button.
The motion detector should click twice, and then make a continuous clicking sound for 5 seconds during which it is collecting data. Move back and forth in front of the motion detector and verify that it is operating correctly. If not contact your instructor.
Figure 1
Apparatus for this experiment
Motion
Detector
PC
LabPr o
4. Printing
One last thing we need to do is print our graphs. Click on the Printer Button on the tool bar . You will see a window where you can annotate your graphs such as putting the group members’ names on them and so on. Since many groups will be printing similar graphs you should put in identifying information here. Click OK when you're ready to print.
Report Format
Turn in one report worksheet with attached graphs for each group. Make sure that the name of each person in the group is put on the worksheet.

Leader: ____________________
Skeptic: ___________________
Report Worksheet
Reporter: ___________________________
Encourager: _________________________
1) Answer the following questions in order. a) Discuss among your group how you should move so that you create a distance vs. time graph that increases with a constant slope. Describe what you will do. Sketch in the space below a graph of what you expect this to look like. The distance should be on the y-axis and the time should be on the x-axis. b) Define velocity. Discuss among your group and then sketch in the space below what you think a graph of the velocity vs. time should look like for the motion in part a). You should pay attention to whether the velocity is positive or negative. c) Define acceleration. Sketch a graph of what you think the acceleration vs. time should look like for this motion.

d) After your discussion, move in the manner you discussed in part a). Record the motion with the experimental equipment. (You may need to adjust the scale on the graph in order to see the data better.) Did you move in the correct way to produce the desired graph? If not, modify your motion so that you do produce the correct graph. e) Did the velocity vs. time and acceleration vs. time graphs appear as you had expected?
(The graphs will be very “noisy” so look at the general trend and not all the bumps and wiggles displayed.) Compare your predictions in parts b) & c) to the experimental graphs displayed. Were you correct in your predictions? Discuss the results.
Print and attach the graphs for the motion discussed in the above questions.

motion.
2) Answer the following questions in order. a) Discuss among your group how you should move so that you create a distance vs. time graph that decreases with a constant slope. Describe what you will do. Sketch in the space below a graph of what you expect this to look like. b) Discuss among your group and then sketch in the space below what you think a graph of the velocity vs. time should look like for the motion in part a). You should pay attention to whether the velocity is positive or negative. c) Sketch a graph of what you think the acceleration vs. time should look like for this

d) After your discussion, move in the manner you discussed in part a). Record the motion with the experimental equipment. (You may need to adjust the scale on the graph in order to see the data better.) Did you move in the correct way to produce the desired graph? If not, modify your motion so that you do produce the correct graph. e) Did the velocity vs. time and acceleration vs. time graphs appear as you had expected?
Compare your predictions in parts b) & c) to the experimental graphs displayed. Were you correct in your predictions? Discuss the results.
Print and attach the graphs for the motion discussed in the above questions.

3) Fill in the blanks in the following questions.
When you walk at a constant velocity the graph of distance vs. time is a line with a constant ________ .
When you walk at a constant velocity the graph of velocity vs. time is a ____________ line.
When you walk at constant velocity the graph of acceleration vs. time is a ____________ line with a value of ________.
4) Open the experiment file called Position Match 1 by clicking on the Open icon , then double clicking on the folder titled Probes & Sensors , then double clicking on the folder labeled Motion Detector and finally double clicking on the file Position Match
1.cmbl. When asked if you wish to save, click on NO.
Try and move in front of the motion detector so that you match the graph. Have each member of your group try to match the graph. Print one copy and label on the graph the places where the velocity was positive, negative and zero. Also label on the graph where acceleration occurred.
Attach the labeled graph.
5) Open the experiment file called Velocity Match. To do so, click on the Open icon.
The directory you opened last time will still be chosen. Double click on the file called
Velocity Match.cmbl. When asked if you wish to save Position Match 1, click on NO.
Try to move so that you match the graph. Have each member of your group try to match the graph.
Print one copy and label on the graph the places where the velocity was positive, negative and zero. Also label on the graph where acceleration occurred.
Attach the labeled graph.