Figure shows a pulley over which is string passes and connected to two masses A and B. Pulley moves up with a velocity `V_(P)` and mass B is also going up at a velocity `V_(B)`.

Find the velocity of mass A if
(a) `V_(P)=5ms^(-1)` and `V_(B)=10ms^(-1)`
(b) `V_(P)=5ms^(-1)` and `V_(B)=-20 ms_(-1)`.

Explanation

(a)` V_(P)=(V_(A)+V_(B))/(2) implies 5 = (V_(A)+10)/(2) implies V_(A)=0`
(b) `5=(V_(A)-20)/(2) implies V_(A)=30 ms^(-1)` .