Question

A stone is released from rest from the top of a
very high tower. In first 3 seconds the stone falls
xm, then for next x m fall, time taken by stone is
(2) 3(3-1) s
(3) 3(v3-VE)S
(4) 3473 - 1)
(1) 3VES​

Answer 1

Given :

Time taken by stone to cover first x m distance = 3s

To Find :

Time taken by stone to cover next x m distance.

Solution :

❒ This question is based on concept of free fall. In this case, Initial velocity of object is taken zero.

• Let stone takes t time to cover first x m distance and takes t' time to cover next x m distance$.$

Second equation of kinematics for free falling object is given by

• h = 1/2 gt²

A] First case :

➙ x = 1/2 gt²

➙ x = g/2 (3)²

➙ x = 9g/2

B] Second case :

Here we can say that stone covers 2x distance in (t + t') rime.

➙ 2x = 1/2 g(t + t')²

➙ 2 × 9g/2 = 1/2 g(t + t')²

➙ 18 = (t + t')²

➙ √18 = 3 + t'

➙ 3√2 = 3 + t'

➙ t' = 3√2 - 3

➙ t' = 3(√2 - 1) s