Answer to Question #300536 in Classical Mechanics for Ben

Question

A balloon is rising vertically upward with a uniform

velocity 'u' as shown in Fig. 11.E22. At a certain

instant, a ball No. 1 is dropped from it, which takes a

4 sec to reach the ground. The moment this ball

strikes the ground, another ball is dropped from the

balloon and this 2nd ball takes 5 sec to reach the

ground. Find the velocity of the balloon 'u' and height

from which both the balls must have been dropped.

Answer 1

$h_1=\frac{gt_1^2}2=80~m,$

$h_2=\frac{gt_2^2}2=125~m,$

$u=\frac{h_2-h_2}{t_1}=11. 25~\frac ms.$