Question

Two point masses connected by an ideal string are placed on a smooth horizontal surfaces as shown in the diagram. A sharp impulse of $10\text{kg-m/s}$ is given to the $5\text{kg}$ mass. The velocity of the $10\text{kg}$ mass just after application of impulse will be $\frac{1}{x}\text{m/s}$, then value of $x$ is

Answer 1

$10\text{kg}$ mass will gain velocity along the string only. Using momentum conservation along the string
$v=\frac{10\cos {60}^{\circ }}{10+5}=\frac{1}{3}\text{m/s}$