Experiment 4
MOTION II

PROCEDURE


Set Up

We follow the same procedures as in Experiment 3 to set up the apparatus and calibrate the motion detector. A few differences are needed to select appropriate files for velocity measurement as opposed to distance.
 

Initiate the LoggerPro Program

1.  Open the LoggerPro program by clicking on this LoggerPro link. A blank graph should appear on the screen.

2.  Double-click anywhere on the graph. This will display a dialog box. Select Velocity for the vertical axis and set the range from -2 to +2 m/sec. Change the Time scale to read 0 to 5 sec. This should give you a blank graph with appropriate units along the axes.

3.  When you are ready to begin, click once on the Collect button in the lower left corner of the screen. You should hear a clicking sound from the detector and a red line should appear on your graph. While the line is being drawn, move your hand in front of the detector to see the result. Each time you click Collect, the previous graph is erased and a new one is displayed.

4.  Open the Worksheet and fill in the header information.


A. Making Velocity Graphs

Experiment 1:  Walking away from the detector

1.  With the LoggerPro window activated, stand about 0.5 meter from the detector, have your partner click Collect, and walk away from the detector slowly and steadily. Practice this a few times until you can generate a graph with none, or just a few erratic segments. Partners should alternate in performing the motions and controlling start-stop in every other run.

NOTE: If you need to alter the velocity or time scales so that the plot fills nearly all of the available space, click anywhere on the graph and change the velocity and/or time ranges which appear in the dialog box.

2.  When you are satisfied with your results, select Store Latest Run from the LoggerPro EXPERIMENT menu.

3.  Repeat the above procedure, but this time walk medium fast and steadily away from the detector.

4.  When you are finished, copy the graph to the clipboard by selecting EDIT....COPY from the LoggerPro menu.

5.  Return to the Worksheet window and PASTE the copied graph into cells A11..E25 on the Worksheet. Do this by placing the cursor in cell A11 and selecting EDIT....PASTE from the Worksheet menu.

NOTE: If you need to resize the graph to make it fit within the designated cells on the Worksheet, first select the graph by clicking on it. Then, grab the lower right handle of the box and move the handle to resize the box as necessary. The box may be moved by clicking anywhere inside it and dragging the outlined image to the desired location.

6.  Ignoring erratic parts of your plots caused by uneven walking or detector error, answer Questions 1 through 3 on the Worksheet beginning at cell A27.

Experiment 2:  Walking toward the detector

7.  Return to the LoggerPro window, and prepare a second graph by walking slowly and steadily toward the detector. Start as far as you can from the detector and still get reliable results.

8.  When you are satisfied with your graph, select Store Latest Run from the LoggerPro EXPERIMENT menu.

9.  Repeat by walking medium fast and steadily toward the detector.

10.  When you are satisfied with your results, COPY and PASTE the graph into cells A51...E65 on the Worksheet. Resize as necessary (see note above).

11.  In the space provided on the Worksheet, answer Question 4. Ignore erratic parts of the plot caused by uneven walking, etc.


B. Making Predictions

1.  Both partners should make their own prediction of the Velocity-Time graph that would result if you

  • walk away from the detector slowly and steadily for 10 seconds

  • stop for 4 seconds

  • walk toward the detector steadily about twice as fast as before

2.  Sketch your prediction on the blank graph provided for this section on the Worksheet. To make the sketch, click the media button (next to the zoom percentage box) and select the line drawing tool.

3.  Compare your prediction with that of your lab partner. Discuss your predictions and resolve any differences.

4.  On the plot, extend the time scale to 20 s by clicking on the graph and setting the x-axis limit. Also under the LoggerPro EXPERIMENT menu, choose Data Collection and set the Length under the Collection Tab to 20 s.

5.  Now do the experiment. Both you and your lab partner should move as described in Step 1 above. When you are satisfied that you have the motion right, set up the motion detector and collect the data for this graph. COPY and PASTE the LoggerPro graph into cells A98...E111 of the Worksheet.

To change the collection time, select the Experiment tab at the top of the screen. Select Data Collection, and then Change Collection Time.

6.  Answer Question 5 in the space provided on the Worksheet.


C. Matching a Velocity-Time Graph

1.  A specific Velocity-Time graph has been prepared for you and stored as a file. Click on the Velocity.Match link to open this LoggerPro window.

2.  If the Collect button is not activated, go to the EXPERIMENT menu, and select Connect Interface.

3.  Now try to move so that you duplicate the Velocity.Match graph. Try a number of times until you match the graph as closely as possible. Note the critical times and velocities in the figure before you begin.

4.  When you are satisfied, COPY and PASTE the matched graph to the Worksheet in cells A126:E143.

5.  In the space provided on the Worksheet, explain how you moved to produce each part of the Velocity.Match graph in Question 6.

6.  Answer Questions 7 through 10 in the appropriate space on the Worksheet.

7.  When you have completed the Worksheet, print it out by selecting PRINT under the FILE menu. Use it to develop your lab report.