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Phy 231
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: ->->->->->->->->->->->-> :
vave = (15 + 0)/2 = 7.5m/s
'ds = 7.5 * 1.5 = 11.25 m
a = 'dv/'dt
'dt = -15 / -10 = 1.5 sec
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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: ->->->->->->->->->->->-> :
vf^2 = v0^2 + 2 * a * 'st
vf^2 = 15^2 + 2 * -10 * -12
vf= 21.6 m/s
vave =(15 -21.6)/2 = -3.3m/s
'dt = 12/ 3.3 = 3.63 sec
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At what clock time(s) will the speed of the ball be 5 meters / second?
answer/question/discussion: ->->->->->->->->->->->-> :
'dt ='dv /a
'dt = -10/ -10 = 1 second
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At what clock time(s) will the ball be 20 meters above the ground?
answer/question/discussion: ->->->->->->->->->->->-> :
vf^2 = v0^2 + 2 * a * 'ds
vf^2 = 15^2 + 2 * -10 * 8
vf = 8.06m/s
'dt = 'vt / a
6.9 / 10 = .69 s
How high will it be at the end of the sixth second?
answer/question/discussion: ->->->->->->->->->->->-> :
v = 5 - 10 * 6 = -45 m/s
vave = -30 / 2 = -15
'ds = -15 * 6 = 90 meters
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That would be -90 meters. We have to that there's a well or a cliff of something.
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25 min
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&#Good responses. See my notes and let me know if you have questions. &#