Uniform Circular Motion Lab
(Download the MS Word version of this document.)
Define uniform circular motion:
Purpose
Procedure
- Find the mass of the washers which are hanging at the end of the string, and the mass of the stopper.
- Have one lab group member carefully swing the stopper on the string in a horizontal circle above his or her head.
- When the radius is constant (that is, the washers are not moving up or down), and the period of rotation is consistent, have another lab group member find the time for 10 revolutions.
- At the end of 10 revolutions, put your finger on the end of the tube to preserve the radius at which the stopper on the end of the string was rotating.
- Measure the radius of the circle (the length of the string).
- Find the period, and then using the period and the radius, find the velocity of the stopper as it rotates.
- Using the mass, velocity, and radius, calculate the centripetal force acting on the stopper. Should you use the mass of the stopper or the mass of the washers in the equation for centripetal force?
- Compare the value you measured for the centripetal force with the weight (not the mass) of the washers.
- Repeat steps b through g for a different radius.
- Record all relevant data in the table below, and answer the questions on the back of this sheet.
Organize your data in the data table below.
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Questions
1. Briefly explain the relationship between the centripetal force and the amount of hanging weight.
2. Calculate the percent difference between the centripetal force and the hanging weight for each part of the lab. Show your work below.
3. In this lab, which quantities did you change and which quantities remained constant throughout the procedure of the lab?
4. How would the speed change if you shortened the period by half as long and kept the radius constant?
5. How would the centripetal force be changed if you kept the mass and velocity constant, but doubled the radius?
6. How would the centripetal force be changed if you kept the mass and radius constant, but increased the speed by 3 times?
