Pre LAB QUESTIONS: DO these before coming to class. They should be on a sheet of paper with the title: Graph Matching.
1. Use a coordinate system with the origin at far left and positive distances increasing to the right. Sketch the distance vs. time graph for each of the following situations:
· An object at rest
· An object moving in the positive direction with a constant speed
· An object moving in the negative direction with a constant speed
· An object that is accelerating in the positive direction, starting from rest
2. Sketch the velocity vs. time graph for each of the situations described above.
One of the most effective methods of describing motion is to plot graphs of distance, velocity, and acceleration vs. time. From such a graphical representation, it is possible to determine in what direction an object is going, how fast it is moving, how far it traveled, and whether it is speeding up or slowing down. In this experiment, you will use a Motion Detector to determine this information by plotting a real time graph of your motion as you move across the classroom.
The Motion Detector measures the time it takes for a high frequency sound pulse to travel from the detector to an object and back. Using this round-trip time and the speed of sound, you can determine the distance to the object; that is, its position. Logger Pro will perform this calculation for you. It can then use the change in position to calculate the object’s velocity and acceleration. All of this information can be displayed either as a table or a graph. A qualitative analysis of the graphs of your motion will help you develop an understanding of the concepts of kinematics.
· Analyze the motion of a student walking across the room.
· Predict, sketch, and test distance vs. time kinematics graphs.
· Predict, sketch, and test velocity vs. time kinematics graphs.
Power Macintosh or Windows PC
Vernier Motion Detector
LabPro or Universal Lab Interface
Part l Preliminary Experiments
1. Connect the Motion Detector to DIG/SONIC 2 of the LabPro or PORT 2 of the Universal Lab Interface. (Note that the second input is used in both cases!)
2. Click on “Short-cut to Vernier software” on the desktop. Then Click on “Logger Pro 2.0”. Once in Logger Pro, go to FILE-OPEN and click on PHYSICS WITH COMPUTERS. Then select Experiment 01 Graph Matching
3. Using Logger Pro, produce a graph of your motion when you walk away from the detector with constant velocity. To do this, stand about 1 m from the Motion Detector and have your lab partner click . Walk slowly away from the Motion Detector when you hear it begin to click.
Part Il Distance vs. Time Graph Matching
7. Open the experiment file Exp 01b Distance Match One. The distance vs. time graph shown will appear.
8. Choose a starting position and stand at that point. Start data collection by clicking . When you hear the Motion Detector begin to click, walk in such a way that the graph of your motion matches the target graph on the computer screen.
10. If you were not successful, repeat the process until your motion closely matches the graph on the screen.
11. Open the experiment file Exp 01c Distance Match Two and repeat Steps 8 – 10, using a new target graph.
Part IIl Velocity vs. Time Graph Matching
13. Open the experiment file Exp 01d Velocity Match One. You will see the following velocity vs. time graph.
15. Choose a starting position and stand at that point. Start Logger Pro by clicking . When you hear the Motion Detector begin to click, walk in such a way that the graph of your motion matches the target graph on the screen. It will be more difficult to match the velocity graph than it was for the distance graph.
16. Open the experiment file Exp 01e Velocity Match Two. Repeat Steps 14 – 15 to match this graph.