Physics 105

March 3, 2003

Today we will continue our focus on the scientific method. We will measure the acceleration of a cart on an inclined plane connected to mass hanging from a pulley. We will measure the acceleration as a function of the mass of the cart, the mass on the pulley, and the angle of inclination. We have studied the 3 extreme cases of this experiment already in previous measurements:

• The Atwood machine (experiment P13): a = (M1 - M2)*g/(M1 + M2)
• The acceleration of a cart (experiment P09): a = m*g/(m + M)
• The acceleration of a cart down an inclined plane (experiment P04): a = g*sin(theta)

In todays experiment we will repeat experiment P09, except with the following differences:

• the track will be tilted
• instead of using the smart pulley we will use the photogate to measure the velocity of the cart

To predict the relation between the acceleration of the cart and the masses involved and the angle of inclination of the track, you will carry out a series of measurements in which these 3 parameters are being changed.

1. To start this experiment, discuss with your partner why the three experiments listed above are extreme cases of the experiment you will be carrying out today.
2. Based on the known dependence of the acceleration in these two extreme cases, make a prediction for the acceleration of the cart up or down the incline as function of the angle of inclinations, the mass of the cart, and the mass hanging on the pulley.
3. Open experiment P09a "Up and Down the Incline" in your handout folder. The instructions for the measurement can be found in the "Experiments Notes" window and on the WEB (under class note: Force and Motion).
4. After carrying out each sequence of measurements in P09a, compare the results with the predictions you made earlier.

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

1. Summary of your observations (use the table format that you can find as part of the WEB pages describing this experiment).
2. Your predicted relation between the measured acceleration and the masses connected to the pulley.
3. A comparison between the predictions made on the basis of your theoretical relation and the measured values.

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

Last updated on Monday, March 3, 2003 10:34