Three blocks with masses $m,2m$ and $3m$ are connected by strings, as shown in the figure. After an upward force $F$ is applied on block $m$, the masses move upward at constant speed $v$. What is the net force on the block of mass $2m$?
($g$ is the acceleration due to gravity)

Q. Three blocks with masses $m,2m$ and $3m$ are connected by strings, as shown in the figure. After an upward force $F$ is applied on block $m$, the masses move upward at constant speed $v$. What is the net force on the block of mass $2m$?
($g$ is the acceleration due to gravity)

Q. A block of mass 2 kg is pulled upwards by a force $F=40N$ as shown in figure. Block is displaced by $2m$. Find work done by the applied force and also due to the force of gravity on the block. (Take $g=10m/s^2$)

Q. Two blocks of mass $m=5kg$ and $M=10kg$ are connected by a string passing over a pulley $B$ as shown. Another string connects the centre of pulley $B$ to the floor and passes over another pulley $A$ as shown. An upward force $F$ is applied at the centre of pulley $A$. Both the pulleys are mass-less. An upward force $F$ is applied in the pulley $A$. Find the acceleration of blocks $m$ and $M$, if $F$ is $100N$.