JEE Previous Year Question

A body $A$, of mass $m=0.1\text{kg}$ has an initial velocity of $3\hat{i}m{s}^{-1}$. It collides elastically with another body, $B$ of the same mass which has an initial velocity of $5jm{s}^{-1}$. After collision, $A$ moves with a velocity $v\to =4\text{(}\hat{i}+\hat{j}\text{)}$. The energy of $B$ after collision is written as $\frac{x}{10}j$. The value of $x$ is

Topic: JEE PYQ

Answer: 1. Full step-by-step solution below.