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Phy 121
Your 'cq_1_02.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_02.1_labelMessages.txt **
The problem:
A ball starts with velocity 4 cm/sec and ends with a velocity of 10 cm/sec.
What is your best guess about the ball's average velocity?
answer/question/discussion: ->->->->->->->->->->->-> scussion (start in the next line):
10+4=14
14/2=
7 cm/sec
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Without further information, why is this just a guess?
answer/question/discussion: ->->->->->->->->->->->-> scussion (start in the next line):
This is just a guess, because you do not know how long the ball rolled for sure.
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If it takes 3 seconds to get from the first velocity to the second, then what is your best guess about how far it traveled during that time?
answer/question/discussion: ->->->->->->->->->->->-> scussion (start in the next line):
vAve=7
7*3=
21 cm
vAve='ds/'dt so 'ds=vAve*'dt
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At what average rate did its velocity change with respect to clock time during this interval?
answer/question/discussion: ->->->->->->->->->->->-> scussion (start in the next line):
10-4=6
6/3=
2cm/s
average rate velocity change equals vave/ 'dt
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You need to use units in your calculations.
6 / 3 would be (6 cm/s) / (3 s).
The result would be 2 (cm/s) / s, which simplifies to 2 cm/s^2, not 2 cm/s.
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Good, but see my note on the units of that last calculation, and the use of units in general.
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