Physics Lab Report - What Keeps a Stopper Moving in a Circle Essay

963 Words Mar 2nd, 2013 4 Pages
What keeps the stopper moving in a circle?
Purpose: Relate the variables involved in uniform circular motion

Hypothesis: I predict that the velocity of the stopper will increase as the radius is shortened.

Rubber stopper with a hole
PVC tube or wooden spool

1. Measure the mass f the stopper and washer, m, and record it in the data and observations section. Then, prepare the experimental apparatus as shown in figure A.
2. Throughout this experiment, you will need to maintain a constant radius of uniform circular motion while ensuring that all of the centripetal force is provided by the clamp and measured on the spring scale. Practice whirling the stopper in a horizontal plane until you can keep the paper clip a short
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10. Whirl the stopper while maintaining a constant force on the scale. Start the stop watch and continue the whirling while monitoring the force. Stop the stopwatch after 30 rev.
11. Record your force and time in data table 2, data run 1. With the paper clip against the bottom of the tube and the string pulled taut, measure the length of the string from the top of the tube to the stopper. Record this as the radius, r, in table 2, data run 1.
12. Change the position of the paper clip to increase the radius uniform circular motion for the stopper. Repeat step 10 at the same spring force as data run 1.
13. Record your force and time in data table 2, data run 1. With the paper clip against the bottom of the tube and the string pulled taut, measure the length of the string from the top of the tube to the stopper. Record this as the radius, r, in table 2, data run 2.
14. Repeat step 12 measure the length of the string from the top of the tube to the stopper. Record this as the radius, r, in table 2, data run 2.

Number of
Revs
n
30
30
30

Table 1
Time
t (s)

14 s
11 s
8s

Radius r (m)

0.3 m
0.3m
0.3m

Number of
Revs

30
30
30

Table 2
Time
t (s)

8.94 s
12 s
14 s

Radius r (m)

0.1 m
0.2 m
0.3 m

3.

4.

1. What does your data show about the relationship between centripetal force and change in speed at a constant radius of circular motion?
1. As the speed increases the centripetal force

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