In the arrangement shown in fig. the ends $P$ and $Q$ of an unstretchable string move downwards with uniform speed $U$. Pulleys $A$ and $B$ are fixed. Mass $M$ moves upwards with a speed.

In the given figure acceleration of wedge $'A'$ is $10\ m/s^2$ along the inclined plane. (There is no friction between $A$ $\&$ $B$ and $A$ $\&$ fixed inclined plane.) Then acceleration of block $'B'$ will ............ $m/s^2$

Find the acceleration of $B$.

Figure shows a boy on a horizontal platform $A$ on a smooth horizontal surface, holding a rope attached to a box $B$ . Boy pulls the rope with a constant force of $50\ N$ . (boy does not slip over the platform). The combined mass of platform $A$ and boy is $250\ kg$ and that of box $B$ is $500\ kg$ . The velocity of $A$ relative to the box $B$ , $5\ s$ after the boy on $A$ begins to pull the rope, will be ............ $m/s$

If all the pulleys are massless and string is ideal, find the reading of spring balance

In the adjoining figure if acceleration of $M$ with respect to ground is $a$, then