cq_1_021

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PHY 121

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 that the average velocity would be the middle ground, so 7 cm/sec.

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

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

Because I don’t know how much distance is traveled or time is spent in getting to that speed. It the speed increased over a very short period of time the average may be higher, if it occurred over a long period of time it may be less.

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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):

6 cm/sec. / 3 sec. = 2 cm/sec. would be the rate at which the velocity increased

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@& The units of (cm/s) / s are not cm/s.

Other than your units error this is the rate at which the velocity increased.

However this isn't the answer to how far the object traveled.*@

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

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

It changed with respect to the clock in that over the course of 3 sec. the velocity increased by 6 cm/sec. So on average it increased by 2 cm/sec.

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@& The units of (cm/s) / s are not cm/s.

Other than your units error this is the rate at which the velocity increased.

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*#&!

@& Not bad but check notes, as well as the discussion at the link below.

&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.

Then please compare your old and new solutions with the expanded discussion at the link

Solution

Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified.

If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#

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