cq_1_021

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PHY 201

Your 'cq_1_02.1' 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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The problem:

A ball starts with velocity 4 cm/sec and ends with a velocity of 10 cm/sec.

• What is your best guess about the ball's average velocity? 

answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):

I would guess the vAve would be (v0 + vF) / 2 = 14 cm/sec / 2 = 7 cm/s.

 

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• Without further information, why is this just a guess?

answer/question/discussion: ->->->->->->->->->->->-> (start in the next line): 

This is just a guess because I do not know positions, times, or acceleration.

 

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• If it takes 3 seconds to get from the first velocity to the second, then what is your best guess about how far it traveled during that time? 

answer/question/discussion: ->->->->->->->->->->->-> (start in the next line): 

In 3 seconds the velocity of the object changed 6 cm/s. Its not vAve, its 'dv. I cannot think of a formula with 'ds that involves 'dv.

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You estimated vAve in the first question. Using that estimate you should easily be able to answer this question.

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• At what average rate did its velocity change with respect to clock time during this interval?

answer/question/discussion: ->->->->->->->->->->->-> (start in the next line): 

a = 'dv / dt = 6 cm/s / 3 s = 2 cm/^2 

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10 mins

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Very good, but see my note on the question you didn't answer.

I'm confident you'll understand what to do there, but if not feel free to submit a revision. Otherwise it won't be necessary for you to do so.

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