Question

balls are dropped from roof of tower if first ball reaches 9th ball is just dropped if n=3/4 height n=
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Answer 1

Answer:

n = 13

Explanation:

The depth a ground from roof of the tower be D.

3/4th height of the tower is 1/4D or D/4 from the roof.

We know the depth of fall is proportional to the square of the time of fall.

Therefore, if the ball takes T seconds to reach the ground, i.e., to fall a depth of D,

in T/2 second, the depth of fall will be D/4.

If balls are dropped at equal interval of time, when the first ball reaches the ground, ninth ball will be just dropped and 5th ball would have travelled D/4 depth.

When the 9th ball reaches the ground, 17th ball will be just dropped and 13th ball would have travelled D/4 depth.

Thus, n = 13