Phy 201
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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: ->->->->->->->->->->->-> :
vf = v0 + a * `dt
vf = 25 m/s + (-10 m/s/s) * 1s
vf = 25 m/s – 10 m/s
vf = 15 m/s
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• What will be its velocity at the end of two seconds?
answer/question/discussion: ->->->->->->->->->->->-> :
vf = v0 + a * dt
vf = 25 m/s + (-10 m/s/s) * 2s
vf = 25 m/s + (-20 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 + 25 m/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 = vAve * `dt
`ds = 15 m/s * 2s
`ds = 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: ->->->->->->->->->->->-> :
After 3rd Second:
vf = v0 + a * `dt
vf = 25 m/s + (-10 m/s/s) * 3s
vf = 25 m/s + (-30 m/s)
vf = -5 m/s/s
After 4th second:
vf = v0 + a * `dt
vf = 25 m/s + (-10 m/s/s) * 4s
vf = 25 m/s + (-40 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: ->->->->->->->->->->->-> :
vf = v0 + a * `dt
0 m/s = 25 m/s + (-10 m/s/s) * `dt
-25 m/s = -10 m/s/s * `dt
2.5 s = `dt
`ds = vAve * `dt
`ds = (25 m/s + 0 m/s) / 2 * 2.5 s
`ds = 12.5 m/s * 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 = (vf + v0) / 2
vAve = (-15 m/s + 25 m/s) / 2
vAve = 5 m/s
`ds = vAve * `dt
`ds = 5 m/s * 4s
`ds = 20 m
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• How high will it be at the end of the sixth second?
answer/question/discussion: ->->->->->->->->->->->-> :
vf = v0 + a * `dt
vf = 25 m/s + (-10 m/s/s) * 6s
vf = 25 m/s + (-60 m/s)
vf = -35 m/s
vAve = (-35 m/s + 25 m/s) / 2
vAve = -5 m/s
`ds = vAve * `dt
`ds = -5 m/s * 6s
`ds = -30 m
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Copy and paste your work into the box below and submit as indicated:
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15 minutes
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&#Very good responses. Let me know if you have questions. &#