System shown in figure is released from rest . Pulley and spring is mass less and friction is absent everywhere. The speed of `5 kg` block when `2 kg` block leaves the constant of with ground is (force constant of spring `k = 40 N//m and g = 10 m//s^(2))`

Options

A. `sqrt2 m/s`
B. `2sqrt2 m/s`
C. `2 m/s`
D. `sqrt2 m/s`

Answer

`(2)`

Explanation

`x = 2g/K` from conservation of mechanical energy,
`mgx = 1/2 Kx^(2) + 1/2 mv^(2) `, here m = 5kg