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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.
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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):
Average velocity is vf + vo and then you divide the answer by 2. (30cm + 0cm)/2 = 30cm/2 = 15cm
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@& 30 cm is not a velocity, so vf is not 30 cm.
30 cm is the change in position.*@
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):
First you take vf = vo t (at). vf = 0 + (6m/sec * 5 sec) = 0 + 30cm = 30 cm. 30 cm is the final velocity.
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By how much did its velocity therefore change?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
The velocity changed from 0cm/sec to 30 cm/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):
You take change in velocity over change in time = 30cm/s/5sec = 6cm/s. The average rate is at which the velocity changed is 6cm/s.
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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):
The velocity would be on the y axis and the time would be on the x axis. The rate would be increasing at 6cm/sec.
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*#&!
@& You started here with an incorrect assumption, misidentifying 30 cm as a velocity.
&#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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