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.
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What will be the velocity of the ball after one second?
answer/question/discussion: ->->->->->->->->->->->-> scussion:
25 m/s - 1 sec( 10 m/s^2) = 15 m/s
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What will be its velocity at the end of two seconds?
answer/question/discussion: ->->->->->->->->->->->-> scussion:
25 m/s - 2 sec (10 m/s^2) = 5 m/s
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During the first two seconds, what therefore is its average velocity?
answer/question/discussion: ->->->->->->->->->->->-> scussion:
(15 m/s + 5 m/s)/2 = 10 m/s
that would be for the second 1-second interval
for the 2-second interval the initial velocity would be 25 m/s
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How far does it therefore rise in the first two seconds?
answer/question/discussion: ->->->->->->->->->->->-> scussion:
10 m/s * 2 sec = 20 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: ->->->->->->->->->->->-> scussion:
25 m/s - 3 sec (10 m/s^2) = -5 m/s
25 m/s - 4 sec (10 m/s^2) = -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: ->->->->->->->->->->->-> scussion:
25 m/s - t(10 m/s^2) = 0 m/s
t = 2.5 sec (or we can tell it's halfway between 2 sec and 3 sec by looking at the velocities)
(25 m/s + 0 m/s)/2 = 12.5 m/s
(12.5 m/s)(2.5 sec) = 31.25 m or roughly 31 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: ->->->->->->->->->->->-> scussion:
since 25 m/s + 4 sec (-10 m/s^2) = -15 m/s
and vAve = (25 m/s + -15 m/s)/2 = 5 m/s
(5 m/s) (4 s) = 20 m
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How high will it be at the end of the sixth second?
answer/question/discussion: ->->->->->->->->->->->-> scussion:
25 m/s + 6 sec (-10m/s^2) = -35 m/s
vAve = (25 m/s + -35 m/s)/2 = -5 m/s
(-5m/s)(6 sec) = -30 m
It will have fallen 30 meters below the point where it was originally thrown, or it will have hit the ground, whichever happened first.
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10 minutes
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No need to submit a revision unless you have questions. You did have one error, which I believe you'll quickly see, but I'm including the link in case it's useful to you:
&#Please compare your solutions with the expanded discussion at the link
Solution
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