cq_1_082

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PHY201

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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: ->->->->->->->->->->->-> :

v0=15

'ds= 12

a=10m/s^2

vf=0

0=15-10'dt

10'dt=15

'dt=15/10

'dt=1.5 seconds to get to its highest point

1.5*15=22.5 meters into the air or 12+22.5=35.5 meters from the position it was thrown from.

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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: ->->->->->->->->->->->-> :

'ds=22.5

vf=v0+a'dt

vf=15-10*3

vf=-15m/s

'dv=0

this is velocity when it reaches its original 12 m position, not when it reaches the ground

I got lost in here somewhere

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At what clock time(s) will the speed of the ball be 5 meters / second?

answer/question/discussion: ->->->->->->->->->->->-> :

'dt=5-1.5= 3.5

vf=15+10(3.5)

vf=50m/s

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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: ->->->->->->->->->->->-> :

just over a second

vf=15+10(4.5)

vf=60m/s

I think it will hit the ground

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15 minutes

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