Question

A ball of mass $Jkg$ is attached to an inextensible string. The ball is released from the position shown in Fig. Find the impulse imparted by the string to the ball immediately after the string becomes taut.

Answer 1

From the figure it is clear that

String will taut when ball comes $2m$.

During this, potential Energy convert to kinetic Energy

$\frac{1}{2}m{v}^2=mgh$

$v=\sqrt{2gh}=\sqrt{2\times 10\times 2}=2\sqrt{10}m/s$

So, impulse $J=mv=1\times 2\sqrt{10}=2\sqrt{10}N.s$