Two blocks A and B having masses `m_(1)=1 kg m_(2)=4 kg` are arranged as shown in the figure The pulleys P and Q are light and frictionless. All the blocks are resting on a horizontal floor and the pulleys are held such that strings remains just taut. At moment t=0 a force F=30 t (N) starts acting on the pulley P along vertically upward direction as shown in the figure The time when the blocks A and B loose contact with ground is `4//x` sec then x is:

Answer

2

Explanation

When blocks loose contact with ground normal reaction on them becomeszero.
(i) When A looses contact `T =10N, F =3t`
or `30t =30, t = 1sec` When `B` looses contact
`2T = 40` or `T = 20, F = 3T` or `30t = 60` or `t = 2 sec`
.