Question

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 $10\, s$. The height of the balloon when the stone was dropped from it is $\left(g=9.8\, ms ^{-1}\right)$

• A. 400 m
• B. 150 m
• C. 100 m
• D. 200 m

Answer 1

Answer: (D)

For a stone which is thrown downwards from a balloon rising upwards, the equation of motion is
$h =-u t+\frac{1}{2} g t^{2}$
$=-29 \times 10+\frac{1}{2} \times 9.8 \times(10)^{2}$
$=-290+490$
$=200\, m$