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Grade 12Mechanics

A football is kicked vertically upward from the ground and a person gazing out of window sees it moving upwards past him at 5 m/s.Window is 15m above the ground.Ignore air resistance And take g=10.

How high does the ball go above ground? and how much time does it take to go from ground to highest point?

Profile image of Chilukuri Sai Kartik
16 Years agoGrade 12
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1 Answer

Profile image of Badiuddin askIITians.ismu Expert
16 Years ago

Dear Chilukuri Kartik

let the initial velocity of football is u m/sec

motion from ground to window

v=5m/sec

h=15m

v2 =u2 -2gh

25=u2 -2*10*15

u2=325

motion from window to highest point

u=5 m/sec , v=0

v2 =u2 -2gh

0=25-2*10*h

h=5/4 m

so total hight =15+5/4 =65/4 m

motion from ground to max hight

u=√325

v=0

v=u-gt

t=√325/10  sec


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