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Phy 201
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.
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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):
The equation for average velocity is vAve= ‘ds/ ‘dt. Since I already have the two different velocities and not just time and position separately, I can just take 10 cm/sec - 4 cm/sec and get 6 cm/sec as the balls average velocity.
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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 best guess, because I don’t actually have the position change and the time change as the ball rolls. I only have the velocity information, after the algebra is finished.
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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
6 cm/sec= ‘ds/ ‘dt (move ‘dt to the left side through multiplication)
6 cm/sec * ‘dt = ‘ds ( plug in the numbers we already have)
6 cm/sec * 3 sec = ‘ds
18 cm = ‘ds is the best guess of how far it traveled during this time.
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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):
vAve= ‘ds / ‘dt
vAve = 18 cm/ 3 sec
vAve= 6 cm/sec is the average rate that velocity changed with respect to clock time.
@& This is the average velocity, not the average rate of change of velocity with respect to clock time.*@
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*#&!
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