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PHY 241
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: ->->->->->->->->->->->-> :
v_f = v_0 + a*`dt
v_f = 25 - 10(1) = 15 m/s
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What will be its velocity at the end of two seconds?
answer/question/discussion: ->->->->->->->->->->->-> :
v_f = 25 - 10(2) = 5 m/s
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During the first two seconds, what therefore is its average velocity?
answer/question/discussion: ->->->->->->->->->->->-> :
vAve = (v_f + v_0) / 2 = (25 + 5) / 2 = 15 m/s
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How far does it therefore rise in the first two seconds?
answer/question/discussion: ->->->->->->->->->->->-> :
15 m/s * 2 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: ->->->->->->->->->->->-> :
v_f = 25 - 10(3) = - 5 m/s = 5 m/s downward
v_f = 25 - 10(4) = -15 m/s = 15 m/s downward
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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: ->->->->->->->->->->->-> :
v_0 = 25, v_f = 0
-10 = -25 / `dt, `dt = 2.5 s
`ds = vAve * `dt = 12.5 * 2.5 = 31.3 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 = (25 + -15) / 2 = 5 m/s
`ds = 5 m/s * 4 s = 20 m above where it was tossed
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How high will it be at the end of the sixth second?
answer/question/discussion: ->->->->->->->->->->->-> :
v_f = 25 - 10(6) = -35 m/s
vAve = -5 m/s
`ds = -5 * 6 = -30 m = 30 m below where it was tossed
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** **
10 min
&#Very good responses. Let me know if you have questions. &#
At what clock time(s) will the ball be 20 meters above the ground?
How high will it be at the end of the sixth second?
answer/question/discussion: ->->->->->->->->->->->-> :
`ds = 8 m
v_0 = 15 m/s
a = -10 m/s^2
v_f = sqrt(15^2 + (2)(-10)(8)) = 8 m/s
-10 = -7 * `dt, `dt = 1.4 s
v_f = 15 - 10(6) = -45 m/s
vAve = -30 m/s
`ds = -30 * 6 = -180 m from initial
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*#&!
&#Your work looks good. Let me know if you have any questions. &#