cq_1_022

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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