Two bodies $A$ and $B$ of masses $10\,\, kg$ and $15\, kg$ respectively kept on a smooth, horizontal surface are tied to the ends of a light string. If $T$ represents the tension in the string when a horizontal force $F = 500\, N$ is applied to $A$ (as shown in figure $1$) and $T'$ be the tension when it is applied to $B$ (figure $2$), then which of the following is true

Two wooden blocks are moving on a smooth horizontal surface such that the block of mass $m$ remains stationary with respect to block of mass $M$ as shown in the figure. The magnitude of force $P$ is 

Three blocks of masses $3\, kg, 2\, kg$ and $1\, kg$ are placed side by side on a smooth  surface as shown in figure. A horizontal force of $12\,N$ is applied to $3\, kg$ block. The  net force on $2\, kg$ block is ............ $N$

Two blocks $A$ and $B$ of masses $3\,m$ and $m$ respectively are connected by a massless and inextensible string. The whole system is suspended by a massless spring as shown in figure. The magnitudes of acceleration of $A$ and $B$ immediately after the string is cut, are respectively

For the given figure what will be the contact force applied by $6\ kg$ block on $4\ kg$ block ............ $N$

Arrangement of two block system is as shown. The net force acting on $1 \,kg$ and $2 \,kg$ blocks are (assuming the surfaces to be frictionless) respectively