A ball is thrown vertically upwards.it goes to a height of 20m and then retuirns to the ground.taking acceleration due to gravity g to be 10m/s2 ,find :
initial velocity of the ball.
final velocity of the ball on reaching the ground and
the total time of journey of ball.

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Answers

2015-08-05T12:04:39+05:30
Maximum height = u² / 2g
⇒ 20 = u² / 2*10
⇒ u² = 20*10*2
⇒ u² = 400
⇒ u = √400
⇒ u = 20 m/s

Final velocity on reaching the ground will be the same as initial velocity with which it was thrown up. So final velocity is 20m/s.

Total time of journey = 2u/g = 2*20*10 = 4s
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