Question

A balloon is moving upwards with velocity 10 ms${}^{-1}$. It releases a stone which comes down to the ground in 11s. The height of the balloon from the ground at the moment when the stone was dropped is:

• A. 495 m
• B. 592 m
• C. 460 m
• D. 500m

Answer 1

The correct option is A 495 m

$u_{stone}=10m/s$ (initial velocity of stone)

$t=11s$

$\therefore H=-ut+\frac{1}{2}g{t}^2$ (H=height of baloon)

$H=-10\times 11+\frac{1}{2}\times 10\times 121=605-110=495m$