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Phy 121
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.
** CQ_1_08.1_labelMessages **
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: ->->->->->->->->->->->-> :
a = vf-v0/`dt ; vf = a`dt + v0 = -10m/s^2*1s+25m/s = -10m/s+25m/s = 15m/s this is in the upward direction.
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• What will be its velocity at the end of two seconds?
answer/question/discussion: ->->->->->->->->->->->-> :
vf = -10m/s^2*2s+25m/s = -20m/s+25m/s = 5m/s
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• During the first two seconds, what therefore is its average velocity?
answer/question/discussion: ->->->->->->->->->->->-> :
vAve = (vf+v0)/2 = (25m/s+5m/s)/2 = 15m/s
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• How far does it therefore rise in the first two seconds?
answer/question/discussion: ->->->->->->->->->->->-> :
`ds = vAve`dt = 15m/s*2s = 30m
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• What will be its velocity at the end of a additional second, and at the end of one more additional second?
answer/question/discussion: ->->->->->->->->->->->-> :
vf = -10m/s^2*3s+25m/s = -5m/s
vf = -10m/s^2*4s+25m/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: ->->->->->->->->->->->-> :
That would be when its velocity is 0.
A=(vf-v0)/`dt ; `dt = (vf-v0)/a = (0m/s-25m/s)/-10m/s^2 = -25m/s / -10m/s^2 = 2.5s
`ds = vAve*`dt = 25m/s / 2 *2.5s = 12.5m/s * 2.5s = 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: ->->->->->->->->->->->-> :
vAve=(vf+v0)/2 = (-15m/s + 25m/s)/2 = 10m/s / 2 = 5m/s
`ds = vAve`dt = 5m/s*4s = 20m
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• How high will it be at the end of the sixth second?
answer/question/discussion: ->->->->->->->->->->->-> :
The velocity after 6 sec is -35 m/s so ave vel for the six sec is -5 m/s and displacement is -30 m.
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&#This looks good. Let me know if you have any questions. &#