$A$ man of mass $60 \ kg$ is standing on a platform of mass $40 \ kg$ as shown in the figure. What force should the man apply on the rope so that he accelerates upward with the platform with an acceleration of $2 \ m/s^2$ (in $N$)? (Take $g = 10 \ m/s^2$)

Two blocks of masses $m$ and $2m$ are connected by a metal wire of negligible mass and having cross-sectional area $A$,passing over a smooth fixed pulley as shown in the figure. If the masses are released from rest,then the stress produced in the wire is:

As shown in the figure,two equal masses each of $2\, kg$ are suspended from a spring balance. The reading of the spring balance will be ......... $kg$.

Two blocks of masses $1\,kg$ and $5\,kg$ are attached to the ends of a massless string passing over a pulley of negligible weight. The pulley itself is attached to a spring balance as shown in the figure. The blocks start moving; during this interval,the reading of the spring balance will be:

Two masses $2 \, kg$ and $3 \, kg$ are attached to the ends of a string passed over a pulley fixed at the top. The tension and acceleration are:

In the figure shown,both blocks are released from rest. Find the time taken for them to cross each other. (Assume $g = 10 \ m/s^2$)