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course Phy 121
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):
I would guess the ball’s average velocity is about 7cm/sec.
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• Without further information, why is this just a guess?
answer/question/discussion (start in the next line):
This is just a guess because we do not have the appropriate information needed to find the actual average velocity.
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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):
I would guess that the ball traveled somewhere around 21cm.
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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):
The ball’s velocity changed 2cm/s during this interval.
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The ball's velocity changed by 6 cm/s during this interval.
So the average rate at which the velocity changed, with respect to clock time, is
ave rate = change in velocity / change in clock time - (6 cm/s) / (3 s) = 2 (cm/s) / s = 2 cm/s^2.
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Very good, but you didn't have the right units and didn't quite have the right terminology on that last calculation, so check my note.
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