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course phy 121
seed 31#$&*
course Phy 121
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/5sec = 6cm/sec
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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):
The final velocity must be 12cm/s.
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• By how much did its velocity therefore change?
answer/question/discussion (start in the next line):
The velocity changed 6cm/sec.
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Initial velocity was zero and final velocity was 12 cm/s. How much did the velocity change?
&&&&&&If the initial velocity was zero and the final velocity was 12 cm/s, then the velocity changed 12cm/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):
30cm / 5sec = 6 cm/sec
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This is the average rate of change of position with respect to clock time.
What is average rate of change of velocity with respect to clock time? Begin with the definition of average rate, and see if you can apply it to this question.
&&&&&&&12cm/s-0cm/s / 6s = average rate of change of velocity with respect to clock time
average rate of change of velocity with respect to clock time = 2cm/s/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 vs. clock time graph would be relatively horizontal, therefore making the velocity much higher than the clock time on average.
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&#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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Good job on the revisions.
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