Answer:
[tex]$ \frac{4\pi R}{V}$[/tex]
Explanation:
Given :
Mass of ball 1 = m
Mass of ball 2 = 2m
Since, R>>>d, the collision is head on.
Therefore, we get
[tex]$ \frac{v_1 -v_2}{V}=\frac{1}{2}$[/tex]
[tex]$ \therefore \frac{\text{velocity of seperation}}{\text{velocity of approach}}= v_1-v_2 = \frac{V}{2}$[/tex]
Relative velocity is given by V/2. So, we get the time when the masses will again collide as
[tex]$ t = \frac{2\pi R}{\frac{V}{2}}=\frac{4\pi R}{V} $[/tex]