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Phy 121
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.
** CQ_1_02.2_labelMessages **
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):
The clock time at the midpoint of this interval is about 9 seconds
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• What is the velocity at the midpoint of this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
The velocity at the midpoint of this interval is 28cm / 9 sec = 3.1 cm / sec as estimated on my graph
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• How far do you think the object travels during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
`ds = `dv (40cm/sec - 16cm/s = 24 cm/sec) * `dt (13 sec - 5 sec = 8 sec) = 192 cm
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Displacement is average velocity * time interval.
It's not change in velocity * time interval. (For example if you travel 3 hours at 60 mph, without changing your velocity, change in velocity * time interval would be zero, which certainly isn't how far you would have traveled).
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• By how much does the clock time change during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
8 seconds
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• By how much does velocity change during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
24 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):
Average rate of change of velocity with respect to clock time or acceleration (aAve) = `dv (24 cm / sec) / `dt (8 sec) = 3 cm / s^2
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• What is the rise of the graph between these points?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
24 cm
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• What is the run of the graph between these points?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
8 sec
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• What is the slope of the graph between these points?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
slope = rise (24 cm) / run (8 sec)
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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):
The slope of the graph tells us that object in question moves at an average rate of 3cm / s^2 the slope corresponds to the values of `dv and `dt
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The slope of the graph tells us that object in question change velocity at an average rate of 3cm / s^2.
That's not how fast the object moves.
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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):
3 cm /s^2
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Very good overall but you have a couple of errors.
&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes. &#
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