A balloon starts rising from the ground with an acceleration of `1.25ms^-2`. After 8 seconds, a stone is released from the balloon. After releasing, the stone will:

Options

A. Reach the ground in 4 second
B. Begin to move down after being released
C. Have a displacement of 50 m
D. Cover a distance of 40 m in reaching the ground

Answer

A

Explanation

When the stone is released from the balloon. Its height
`h = 1/2 at^2 = 1/2 xx 1.25 xx (8)^2 = 40m`
and velocity v = at = `1.25 xx 8 = 10 m//s`
Time to reach the ground
`h = ut + 1/2 g t^2`
`rArr 40 = (-10)t + 1/2 xx 10 xx t^2`
rArr t^2 - 2t - 8 = 0 rArr t = 4, -2`
t = 4sec