Question

A healthy youngman standing at a distance of 7 m from 11.8 m high building sees a kid slipping from the top floor. With what speed (assumed uniform) should he run to catch the kid at the arms height (1.8)m ?

Answer 1

At point B(i,e. over 1.8 m from ground), the kid should be caught.

For kid : Initial velocity, u = 0

Acceleration due to gravity = 9.8 $m/s^2$

Distance, S = 11.8 -1.8 = 10 m

Now, $S=ut+\frac{1}{2}a{t}^2$

$\Rightarrow 10=0+\frac{1}{2}\left(9.8\right)t^2$

$\Rightarrow t^2=\frac{10}{4.9}=2.04$

$\Rightarrow t=1.42s$

In this time man has to reach at the bottom of the building.

$\therefore Velocity=\frac{s}{t}=\frac{7}{1.42}=4.9m/s$