cq_1_71

Your 'cq_1_7.1' 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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Assn 7 Seed 1

A ball falls freely from rest at a height of 2 meters. Observations indicate that the ball reaches the ground in .64 seconds.

Based on this information what is its acceleration?

answer/question/discussion:

a=`dv/`dt, but first vAve=`ds/`dt, vAve= 2/.64= 3.125. vf= 2*vAve since v0=0, so vf= 6.250m/s.

Then `dv= vf-v0, so `dv= 6.250m/s. a=6.250m/s / .64s = 9.8m/s^2

Is this consistent with an observation which concludes that a ball dropped from a height of 5 meters reaches the ground in 1.05 seconds?

answer/question/discussion:

No, because the aAve for this scenario is aAve= 5/1.05= 4.76m/s. vf= 2*aAve= 9.52. `dv=9.52m/s

a= 9.52/1.05= 9.07 cm/s^2

Are these observations consistent with the accepted value of the acceleration of gravity, which is 9.8 m / s^2?

answer/question/discussion:

The first one is, but the second one is not.

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20min

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Excellent work.