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Phy 121
Your 'cq_1_03.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_03.1_labelMessages.txt **
The problem:
A ball starts with velocity 0 and accelerates uniformly down a ramp of length 30 cm, covering the distance in 5 seconds.
What is its average velocity?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
(30cm)/5s =6cm/s
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If the acceleration of the ball is uniform then its average velocity is equal to the average of its initial and final velocities.
You know its average velocity, and you know the initial velocity is zero.
What therefore must be the final velocity?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
60cm/s because (60+0)/2 =30
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The average velocity is 6 cm/s.
If the average velocity was 30 cm/s this would be correct; however there is no 30 cm/s velocity involved here. There is a 30 cm displacement, but it doesn't occur in one second.
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By how much did its velocity therefore change?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
60cm/s-0cm/s =60cm/s
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At what average rate did its velocity change with respect to clock time?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
(60cm/s - 0cm/s)/(5s) =60cm/s^2
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What would a graph of its velocity vs. clock time look like? Give the best description you can.
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
it would be increasing at an increasing rate with clock time on the x axis and velocity on the y axis
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*#&!
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If the acceleration is uniform then velocity changes at a constant, not an increasing rate.
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Your logic was mostly correct, but you assumed a 30 cm/s average velocity when the average velocity is 6 cm/s.
Please take a few minutes to correct this.
&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes. &#
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