Question

A balloon is moving vertically with a velocity of $4\text{m/s}$. When it is at a height of $h$, a ball is gently released from it. If it reaches the ground in $4\text{s}$, the height of the balloon when the body is released is

• A. $80\text{m}$
• B. $96\text{m}$
• C. $64\text{m}$
• D. $78\text{m}$

Answer 1

The correct option is C $64\text{m}$

As both the balloon and ball are moving upwards together.
The ball initially will acquire the velocity of balloon before falling.
Assuming upward direction to be positive.
Initial velocity of balloon is +4 m/s
By using second equation of motion, we get
$-h=4\times 4-\frac{1}{2}10(4{)}^2$
$\Rightarrow h=64m$