Q.
Three masses $M =100 \,kg , m _1=10\, kg$ and $m _2=20 \,kg$ are arranged in a system as shown in figure. All the surfaces are frictionless and strings are inextensible and weightless. The pulleys are also weightless and frictionless. A force $F$ is applied on the system so that the mass $m _2$ moves upward with an acceleration of $2\, ms ^{-2}$. The value of $F$ is :
$\left(\right.$ Take $\left.g =10\, ms ^{-2}\right)$
Solution: