cq_1_091

Phy 201

Your 'cq_1_09.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.

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A ball accelerates uniformly as it rolls 20 cm down a ramp, starting from rest, in 2 seconds.

• What are its average velocity, final velocity and acceleration?

answer/question/discussion: ->->->->->->->->->->->-> :

vAve = 20 cm / 2s

vAve = 10 cm/s

10 cm/s = (vf + v0) /2

20 cm/s = vf + 0 cm/s

vf = 20 cm/s

aAve = `dv / `dt

aAve = 20 cm/s / 2s

aAve = 10 cm/s/s

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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: ->->->->->->->->->->->-> :

vAve = 20 cm / 1.94s

vAve = 10.31 cm/s

10.31 cm/s = (vf + 0 cm/s) / 2

vf = 20.62 cm/s

aAve = 20.62 cm/s / 1.94s

aAve = 10.63 cm/s/s

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• What is the percent error in each?

answer/question/discussion: ->->->->->->->->->->->-> :

3% for final velocity – (20 cm/s) / (20.62 cm/s) = .9699

6% for acceleration – (10 cm/s) / (10.63 cm/s) = .94

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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: ->->->->->->->->->->->-> :

N/A

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• If the percent errors are different explain why it must be so.

answer/question/discussion: ->->->->->->->->->->->-> :

The percent error for acceleration is twice that of final velocity. Acceleration twice has to use the revised number in its calculation, versus, final velocity’s one time.

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15 minutes

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Very well done.