Your 'cq_1_05.1' 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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cq_1_051
Your 'cq_1_05.1' 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 accelerates at 8 cm/s^2 for 3 seconds, starting with velocity 12 cm/s.
· What will be its velocity after the 3 seconds has elapsed?
answer/question/discussion: starting velocity + the rate of acceleration for 3 seconds = 12cm/s = 24cm/s = 36cm/s
· Assuming that acceleration is constant, what will be its average velocity during this interval?
answer/question/discussion: During this 3 second interval, the ball’s velocity changed from 12 cm/s to 36cm/s. The final velocity – the initial velocity divided by 2 (to average obviously) would be (36cm/s – 12cm/s) / 2 = 12cm/s
you average two number by adding them and dividing by 2, not subtracting and dividing by 2.
How does this change your answer?
&&&& during this 3 second interval, the average velocity will be (v0+vf)/2 = (12cm/s + 36cm/s) / 2 = 24cm/s
· How far will it travel during this interval?
answer/question/discussion: At an average rate of 12cm/s for 3 seconds the ball will travel 36cm.
The ball starts out at 12 cm/s and speeds up. Its average velocity will clearly be greater than 12 cm/s (see also above note).
&&&& If the ball accelerates at 24cm/s for 3 seconds, it will 72cm.
24 cm/s is the average velocity, not the acceleration. Multiplying average velocity by time interval will, as in your solution, give you the change in position.
Acceleration and time interval would give you change in velocity, not change in position.
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10 min
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Good work except for one error. See my notes.
&#Copy this question into a text editor or word processor, insert your answers to my questions, any revisions you find necessary, and/or questions of your own, and mark your insertions with &&&&. Then submit using the form for this seed question.
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5 min
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Good. See my note.