Question

A body standing on the top of a tower throws up a ball with a velocity u. The ball reach to foot of the tower with a velocity 3u. The height of tower is​

Answer 1

Answer:

t=4u/g

Explanation:

First of all if a ball is thrown upwards with velocity u, it will reach the ground with a final velocity of -3u since the direction of velocity is opposite, therefore the negative sign. The question therefore should mention “speed” instead of velocity.

Secondly, the answers that already have been written are too complex so i suggest that you read my answer.

Considering upward direction as positive,

Initial velocity = u

Final velocity = v= -3u

Acceleration = -g (since acceleration is directed downwards) =-9.8 m/s^2

Let the time of journey be ‘t’

By first equation of motion,

v=u+at

-3u=u-gt

Rearranging,

gt=4u

Therefore t=4u/g

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