Question

A ball, thrown by a boy, is caught by another boy in 2s. What is the maximum height attained by the ball?

• A. 10 m
• B. 5 m
• C. 20 m
• D. 7.5 m

Answer 1

The correct option is B 5 m

The formula for time of flight is

$T=\frac{2u\sin \theta }{g}$

It is given that time is 2 seconds. So,

$2=\frac{2u\sin \theta }{g}$

$g=u\sin \theta$

Squaring both sides

$g^2=u^2{\sin }^2\theta ........\left(1\right)$

Height travelled is

$H=\frac{u^2{\sin }^2\theta }{2g}$

$H=\frac{g^2}{2g}\left(from1\right)$

$H=\frac{g}{2}=5m$