Phy 201
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A ball accelerates uniformly as it rolls 20 cm down a ramp, starting from rest, in 2 seconds.
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What are its average velocity, final velocity and acceleration?
answer/question/discussion: vAve = 20 cm / 2 s = 10 cm /s, vf = 10 cm/s * 2 = 20 cm/s, a = (20 cm/s - 0) / 2 s = 10 cm/s^2
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If the time interval is in error so that it is 3% longer than the actual time interval, then what are the actual values of the final velocity and acceleration?
answer/question/discussion: vf = 9.85 cm /s * 2 = 19.7 cm/s, a = 19.7 cm/s / 2.03 s = 9.7 cm/s^2
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What is the percent error in each?
answer/question/discussion: % error vf = 20 cm/s / 19.7 cm/s = 1.0 % , % error a = 10 cm/s^2 / 9.7 cm/s^2 = 1.0 %
The error is the difference between the two quantities, not their ratio.
The percent error is the difference between the two quantities, as the percent of that quantity.
What is the difference between the two velocities?
What is this difference as a percent of the velocity?
Answer the same series of questions for the acceleration.
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If the percent error is the same for both velocity and acceleration, explain why this must be so.
answer/question/discussion: the velocity and the acceleration of the object are intertwined. If an object's velocity changes it is accelerating, so the percent errors should be the same.
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If the percent errors are different explain why it must be so.
answer/question/discussion: if the percent error for the acceleration is greater than that of the velocity it shows that the velocity of the object is changing rapidly.
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10 minutes
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You did not calculate the percent difference is correctly.
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