A mass m with velocity v approaches a stationary mass M along the x -axis. The masses bounce of each other elastically. Assume that the motion takes place in one dimension along the x axis, and vf and Vf represent the final velocities of masses m and M along the x -axis. Which of the following are true?
1
vf = v, Vf = v
2
vf = 0, Vf = v
3
\({v_f} = \frac{{\left( {m - M} \right)v}}{{m + M}},{V_f} = \frac{{2mv}}{{m + M}}\)
4
\({v_f} = \frac{{mv}}{{m + M}},\,{V_f} = \frac{{Mv}}{{m + M}}\)