Question

A stone is dropped from the top if a cliff and is found to travel ` 44. 1m` in the last second before it reaches the ground . Fing the height of the cliff.

Answer 1

Let (S) be the height of cliff and (t) be the total time taken by stone while falling from top to bottom of the cliff. Here, initial velocit, ` u = 0,
acceleration ` a= 9.8 ms^(-20` , D_1 = 44 . 1 m.
As, ` D_1 = u = a/2 ( 2t-1)` ,
:. 44.1 =0 + (9.8) /2 ( 2 t-1) = 4.9 ( 2 t-1)`
On soving, ` t= 5 s`
:. ` S = ut + 1/2 at^2 = 0 xx 5 + 1/2 xx 9/8 xx 5^2`
`= 4.9 xx 5^2 = 122.5 m`.