Phy 201
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 = (final position – initial position) / time elapsed
average velocity = (30 cm – 0 cm) / 5 seconds = 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):
(6 cm/sec) / 5 = 1.2 cm/sec / sec
6 cm/sec + 1.2 cm/sec + 1.2 cm/sec = 8.4 cm/sec
if you average v0 = 0 and vf = 8.4 cm/s you don't get v_Ave = 6 cm/s.
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• By how much did its velocity therefore change?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
(8.4 cm/sec – 6 cm/sec) = 2.4 cm/sec
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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):
(6 cm/sec) / 5 sec = 1.2 cm/sec / sec
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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):
A graph of the velocity vs. clock time would have the velocity on the y-axis, and the clock times on the x-axis. The line would start at the origin, indicating at t=0, velocity is 0 cm/sec. The line would rise continuously toward the right, with a veer to the right, indicating acceleration.
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30 minutes
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You're not doing badly but there are a couple of ideas you need to iron out. You should be able to revise this and the last couple of 'seed' questions fairly easily, since you basically understand what's going on and just need to refine a couple of ideas. Let me know if you have questions.
&#Please compare your 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. &#