A smooth washer impinges at a velocity `'v'` on a group of three smooth identical blocksresting on a smooth horizontal surface as shown in fig. Mass of each block is equal to mass of the washer. The diameter of the washer and its height are equal to edge of the block. The velocity of blocks `(2)` and `(3)` after collision is

Options

A. `v`
B. `(v)/(sqrt(2))`
C. `(v)/(2)`
D. `2v`

Answer

B

Explanation

Washer collides with the block `(2)` and `(3)` symmetrically, and both blocks are of equal mass therefore both will move with the same speed. After collision the situation of the blocks are shown.

Using conservation of momentum along `x`-axis
`m v = m v^(1) cos 45 + m v^(1) cos 45`
`v = 2v^(1) xx (1)/(sqrt(2))`
`v^(1) = (v)/(sqrt(2))`