Question

A small ball B of mass m is suspended with light inelastic string of length L from a block A of same mass m which can move on smooth horizontal surface as shown in the figure. The ball is displaced by angle $\theta$ from equilibrium position & then released.

The displacement of block when ball reaches the equilibrium position is

• A. $\frac{\text{L sin }\theta }{2}$
• B. $\text{L sin }\theta$
• C. L
• D. None of these

Answer 1

Answer: (A)

$\Delta {\text{x}}_{\text{cm}}=0$
$0=-\left(\text{L sin}\theta -\text{x}\right)\text{m}+\text{mx}$
$\text{L sin}\theta -\text{x}=\text{x}$
$2\text{x}=\text{L sin}\theta$
$\text{x}=\left(\text{L sin}\theta \right)/2$