Phy 231
Your 'cq_1_08.1' 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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A ball is tossed upward with an initial velocity of 25 meters / second. Assume that the acceleration of gravity is 10 m/s^2 downward.
• What will be the velocity of the ball after one second?
answer/question/discussion: ->->->->->->->->->->->-> :
25m/s – (10m/s^2*1s) = 25m/s-10m/s = 15m/s
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• What will be its velocity at the end of two seconds?
answer/question/discussion: ->->->->->->->->->->->-> :
25m/s – (10m/s^2*2s) = 25m/s-20m/s = 5m/s
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• During the first two seconds, what therefore is its average velocity?
answer/question/discussion: ->->->->->->->->->->->-> :
initial velocity = 25m/s; final velocity = 5m/s
vAve = 25m/s+5m/s / 2 = 30m/s / 2 = 15m/s
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• How far does it therefore rise in the first two seconds?
answer/question/discussion: ->->->->->->->->->->->-> :
15m/s*2s = 30m
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• What will be its velocity at the end of an additional second, and at the end of one more additional second?
answer/question/discussion: ->->->->->->->->->->->-> :
3 seconds: 25m/s – (10m/s^2*3s) = 25m/s-30m/s = -5m/s
4 seconds: 25m/s – (10m/s^2*4s) = 25m/s- 40m/s = -15m/s
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• At what instant does the ball reach its maximum height, and how high has it risen by that instant?
answer/question/discussion: ->->->->->->->->->->->-> :
To be at maximum height, the velocity will equal 0, so:
25m/s – (10m/s^2*xs) = 0m/s
-25m/s = -10m/s^2 (x)
X= 2.5 seconds
Average velocity: 25m/s +0m/s / 2 = 25m/s / 2 = 12.5m/s
12.5m/s *2.5 s = 31.25m
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• What is its average velocity for the first four seconds, and how high is it at the end of the fourth second?
answer/question/discussion: ->->->->->->->->->->->-> :
initial: 25m/s
final: -15m/s
vAve = -15m/s +25m/s / 2 = 10m/s / 2 = 5m/s
5m/s *4 s = 20m
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• How high will it be at the end of the sixth second?
answer/question/discussion: ->->->->->->->->->->->-> :
25m/s – (10m/s^2*6s) = 25m/s-60m/s = -35m/s
vAve = 25m/s -35m/s / 2 = -10m/s / 2 = -5m/s
-5m/s *6sec = -30m distance cannot be negative, so it is back on the ground
This is a measure of position, not distance. If there's a hole in the ground, then a negative position is certainly possible.
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20 minutes
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&#This looks good. See my notes. Let me know if you have any questions. &#