Physics 105

March 17, 2003

Today we will continue our focus on the scientific method. We will measure the velocity of a cart on an inclined plane and study how the velocity distribution is changed when we change the angle of inclinations, the position, and the mass of the cart. In order to do this we will carry out experiment P10a.

You are expected to obtain the following data:

1. for at least three angles of inclination, you are expected to have data showing the mesured velocity at various distances along the track.
2. for at least one angle of inclination you are expected to have velocity data at difference positions for at least three different masses of the cart.

The height above the table of the cart can be calculated from the measured position along the track. For example, if the height of the end of the track above the table is H, and the track is 1.2 m long, then the height h of the cart when it is positioned a distance x from the end of the track is equal to:

h = x*(H/1.20)

Using the calculated height we can study the relation between the change in height (h0-h1) and the change in velocity (v0-v1). Using the data you collected create the following graphs:

1. (h0-h1) vs (v0-v1)
2. (h0-h1) vs (v0-v1)^2
3. (h0-h1) vs sqrt(v0-v1)
4. (h0-h1) vs 1/(v0-v1)
5. (h0-h1) vs 1/(v0-v1)^2
6. (h0-h1) vs 1/sqrt(v0-v1)

Use Excel to create these graphs and reduce the amount of work required to calculate the numbers involved. Which relation is linear?

At the end of the class I would like to receive from each of you the following information:

1. Summary of your observations.
2. Your predicted relation between the measured velocity and the change in height of the track.
3. A comparison between the predictions made on the basis of your theoretical relation and the measured values.
The next lab report will be due on March 24, and should describe experiment P13, P09a, and P10a. The focus should be on the application of the scientific method to produce a theory that describes the data you have collected. I want to see:
• A description of the experiments
• A summary of the data collected
• A discussion on the errors in your data
• A discussion of the process used to obtain the theoretical prediction
• A comparison between your theory and your experimental data

© Frank L. H. Wolfs, University of Rochester, Rochester, NY 14627, USA

Last updated on Monday, March 17, 2003 7:58