Two block `A` and `B` of masses `1kg` and`2kg` respectively are connected by a string, passing over a light frictionless pulley as shown. Another string connect the center of pulley. Both the blocks are resting on a horizontal floor and the pulley is help such that string remains just taut. At moment `t = 0`, a force `F = 20 t` starts acting on the pully along vertically upwards direction as shown in figure.Calculate

(a) velocity of `A` when `B` loses contact with the floor.
(b) height raised by the pulley upto that instant.
(Take =`g =10 m//s^(2))`

Answer

`[5 m//s, 5//6 m]`