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Angular Velocity of a Strap __
Question: What is the evidence for or against the hypothesis that the angular velocity of a strap changes as the strap rotates? What is the evidence that the angular velocity changes at a constant rate?
Give your best answer based on your data for the single trial that lasted longest--the one where the strap kept moving longer than any other. For now we won't worry about the other trials. Include a copy of your data for that trial and explain specifically how that data supports your answer.
The longest trial I recorded resulted in 630 ° of rotation in 6.06 seconds. The strap ended with an angle of 90 ° from the start point. It passed the start point at the following clock times in seconds:
.84375, .90625, 1.34375
It came to rest at approximately 90 ° at clock time 2.96875
Each rotation took more time than the one before it. This would fail to reject the hypothesis that the angular velocity of a strap changes as the strap rotates. It suggests that the velocity is decreasing. This can be demonstrated by calculating the velocity in degrees of travel per second:
180 ° / .0625 sec = 213° /sec
180 ° / .4375 sec = 199° /sec
180 ° / 1.625 sec = 134° /sec
90 ° / 1.84375 sec = 49° /sec
Calculating the acceleration as the change in angular velocity divided by the clock time, I do not see a constant rate of change in velocity with respect to change in time:
15 °/ .90625 = 16.6 ° / sec^2
65 °/ .1.34375 = 48.4 ° / sec^2
85 °/ 1.84375 = 46.1 ° / sec^2
Very good responses. You gave a detailed and mostly correct analysis, which is exactly the way you would connect your results to the question at hand.
However note that average angular acceleration is change in angular velocity / change in clock time, not change in angular velocity / clock time.
Would this make any difference in your conclusions?