Phy 201
Your 'cq_1_02.2' 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 graph is constructed representing velocity vs. clock time for the interval between clock times t = 5 seconds and t = 13 seconds. The graph consists of a straight line from the point (5 sec, 16 cm/s) to the point (13 sec, 40 cm/s).
• What is the clock time at the midpoint of this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
(5sec + 13sec) / 2 = 9 sec
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• What is the velocity at the midpoint of this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
(16 cm/sec + 40 cm/sec) / 2 = 28 cm/sec
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• How far do you think the object travels during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
(28 cm/sec – 16 cm/sec) / 4 = 3 cm /sec
1st second = 16 cm
2nd second = 19 cm
3rd second = 22 cm
4th second = 25 cm
16 cm + 19 cm + 22 cm + 25 cm = 82 cm
this isn't a bad estimate but it's an underestimate (see note on preceding cq problem).
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• By how much does the clock time change during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
(9 sec – 5 sec) = 4 sec
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• By how much does velocity change during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
28 cm/sec – 16 cm/sec = 12 cm/sec
change in velocity runs from the beginning of the interval to the end; velocity at the end is not 28 cm/s.
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• What is the average rate of change of velocity with respect to clock time on this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
(12 cm/sec) / 4sec = 3 cm/sec / sec
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• What is the rise of the graph between these points?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
28 – 16 = 12
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• What is the run of the graph between these points?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
9 – 5 = 4
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• What is the slope of the graph between these points?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
12 / 4 = 3
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• What does the slope of the graph tell you about the motion of the object during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
It is increasing in velocity over time.
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• What is the average rate of change of the object's velocity with respect to clock time during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
(12 cm/sec) / 4 sec = 3 cm/sec /sec
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20 minutes
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&#Please compare your solutions with the expanded discussion at the link
Solution
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