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phys 201
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: ->->->->->->->->->->->-> :
a = (vf - v0) / dt
v0 = 25 m/s
a = -10 m/s
dt = 1 s
vf = ?
-10 m/s = (vf - 25 m/s) / 1s
vf= 15 m/s
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• What will be its velocity at the end of two seconds?
answer/question/discussion: ->->->->->->->->->->->-> :
a = (vf - v0) / dt
v0 = 25 m/s
a = -10 m/s
dt = 2 s
vf = ?
-10 m/s = (vf - 25 m/s) / 2s
-20 m/s = vf - 25 m/s
vf = 5 m/s
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• During the first two seconds, what therefore is its average velocity?
answer/question/discussion: ->->->->->->->->->->->-> :
vAve = (vf + v0) / 2
vAve = (5 m/s + 25m/s) / 2
vAve = 15 m/s
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• How far does it therefore rise in the first two seconds?
answer/question/discussion: ->->->->->->->->->->->-> :
ds = (vf + v0) / 2 * 2
ds = (25 m/s + 5 m/s) = 30 m
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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: ->->->->->->->->->->->-> :
a = (vf - v0) / dt
v0 = 25 m/s
a = -10 m/s
dt = 3s, 4 s
vf = ?
-10 m/s = (vf - 25 m/s) / 4s
-40 m/s = vf - 25 m/s
vf = -15 m/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: ->->->->->->->->->->->-> :
a = (vf - v0) / dt
-10 m/s = (0 m/s - 25 m/s) / dt
dt = 2.5 s
ds = (vf + vo) / 2 * dt
ds = (0 + 25 m/s) / 2 * 2.5 s
ds = 31.25 m
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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 = (-15 m/s + 25 m/s) / 2
vAve = 5 m/s
ds = (25 m/s + (-15m/s)) / 2 * 4s
ds = 20 m
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• How high will it be at the end of the sixth second?
answer/question/discussion: ->->->->->->->->->->->-> :
-10 m/s = (vf - 25 m/s) / 6s
-60 m/s = vf - 25 m/s
vf = -35 m/s
ds = (25 m/s + (-35m/s)) / 2 * 6s
ds = -30 m
It will have hit the ground already.
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*#&!
&#Very good responses. Let me know if you have questions. &#