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

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JEE Main 8 January 2020, Shift 1, Physics Q22

Question 22 of 75 in this shift, Physics question 22 of 25, Section B.

A body A, of mass m = 0.1 kg has an initial velocity of

3\hat{i}

^{-1}

. It collides elastically with another body, B of the same mass which has an initial velocity of

5\hat{j}

^{-1}

. After collision, A moves with a velocity

\vec{v} = 4(\hat{i}+\hat{j})

. The energy of B after collision is written as

\frac{x}{10}

J. The value of

x

is ______.

Official answer

1.00

NTA final key (Jan 2020).