Two identical balls `A` and `B`. each of mass `2 kg` and radius `R`, are suspended vertically from inextensible strings as shown in Fig. The third ball `C` of mass `1 kg` and radius `r=(sqrt(2)-1)R` falls and hits `A` and `B` symmetrically with `10 m//s`. Speed of both `A` and `B` just after the collision is `3 m//s`.

The value of coefficient of restitution is

Options

A. `1/4`
B. `1/sqrt(2)`
C. `sqrt(2)-1`
D. `1/2`

Answer

D

Explanation

`e=("Velocity of separation")/("Velocity of approach")`
`implies e=(3costheta+V_(C)^(')sintheta)/(10sintheta)impliese=(3+2)/10=1/2`