Q. A balloon is rising vertically up with a velocity of $29\ ms^{- 1}$. A stone is dropped from it and it reaches the ground in 10 seconds. The height of the balloon when the stone was dropped from it is $($ $g = 9.8\ ms^{- 2})$
A) $100\ m$
B) $200\ m$
C) $400\ m$
D) $150\ m$
Explanation
(b) For stone to be dropped from rising balloon of velocity $29\ m/s$
$u = - 29\ m/s,\ t = 10sec$
$\therefore h = - 29 \times 10 + \frac{1}{2} \times 9.8 \times 100$
$= - 290 + 490 = 200\ m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.