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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: ->->->->->->->->->->->-> (start in the next line):
My best guess about the ball’s average velocity is 7 cm /s.
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• Without further information, why is this just a guess?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
Because to find 7 cm/s I simply took the average of the two velocities given by: 10cm/s + 4 cm/s = 14 cm/s / 2 = 7 cm/s. We know that vAve = ‘ds / ‘dt so we must have more than just the initial and final velocities as information.
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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: ->->->->->->->->->->->-> (start in the next line):
vAve = ‘ds / ‘dt
7 cm/s = ‘ds / 3s
Multiply both sides by 3s so,
21 cm = ‘ds
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• At what average rate did its velocity change with respect to clock time during this interval?
answer/question/discussion: ->->->->->->->->->->->-> (start in the next line):
Average rate of velocity change = (vfinal - vinitial) / time = (10 cm/s - 4cm/s) / 3s = (6cm/s) * (1/ 3s) = 2cm/s^2.
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&#Very good work. Let me know if you have questions. &#