A balloon starts rising from ground with an acceleration of `1.25 m//sec^2`. A `8` seconds a stone is released from the balloon. The maximum height from the ground reached by stone will be.

Options

A. 40 m
B. 50 m
C. 45 m
D. 55 m

Answer

C

Explanation

When a particle separates from a moving body it retains the velocity of the body but not its acceleration. At the instant of released the balloon is `s = (1)/(2) xx (1.25) xx 64 = 40 m` above the ground and is having an upward velocity `= 1.25 xx 8 = 10 m//sec`. For the motion of stone from the balloon to the highest point,
`u = 10 m/sec`
`a = -g = -10 m//sec^2`
`v = 0` using `v^2 - u^2 = 2as`
`0 - 100 = -2 xx 10 xx s`
`s = 5` metres
`:.` maximum height from ground `= 40 + 5 = 45 m`.