Two small, identical steel balls collide completely elastically. Initially, ball $1$ is moving with velocity $v_1$ directly toward ball $2,$ and ball $2$ is stationary.

$(0)$

What are the final velocities of ball $1$ and ball $2,$ respectively?

$-v_1$ and $2v_1$

$\frac{v_1}{2}$ and $\frac{v_1}{2}$

$0$ and $v_1$

$v_1$ and $2v_1$

$-v_1$ and $0$