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Phy 241
Your 'cq_1_08.2' 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_08.2_labelMessages **
A ball is tossed upward at 15 meters / second from a height of 12 meters above the ground.
Assume a uniform downward acceleration of 10 m/s^2 (an approximation within 2% of the 9.8 m/s^2 acceleration of gravity).
How high does it rise and how long does it take to get to its highest point?
answer/question/discussion: ->->->->->->->->->->->-> :
v_0 = 15 m/s
g = -10 m/s
h = 12 m above the ground
After one second the ball's velocity is 5 m/s. At 1.5 seconds the ball reaches its highest point and has traveled 15 meters
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The ball would have to average 10 m/s to reach height 15 meters after 1.5 seconds. However that is not its average velocity during this interval.
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How fast is it then going when it hits the ground, and how long after the initial toss does it first strike the ground?
answer/question/discussion: ->->->->->->->->->->->-> :
t=0, v_0 =15 m/s, s = 0
t=1, v_1 = 5 m/s, s= 10 m
t= 2, v_2 = -5 m/s, s= 10 m
t= 3, v_3 = -15 m/s, s= -5 m
t=4, v_4 = -25 m/s, s= -20 m
Somewhere between 3 and 4 seconds the ball hits the ground. Assuming uniform downward acceleration, the ball reaches -12 meters at 3.4 seconds
at a velocity of 19 m/s in the downward direction
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There are valid and invalid ways to get these results.
A valid solution would involve the equations of uniformly accelerated motion, or alternatively the results of appropriate integrations and/or differentiations.
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At what clock time(s) will the speed of the ball be 5 meters / second?
answer/question/discussion: ->->->->->->->->->->->-> :
when t = 1 and t = 2. The difference is t=2 is in the downward direction
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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: ->->->->->->->->->->->-> :
the ball is 20 meters above the ground when t = .8 seconds
The ball hits the ground at 3.4 s, so in order to find how high the ball is at the 6th second, we would have to figure deflection and other principles as well.
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Much of your work is good, but check my last note.
&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes. &#
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