$A$ man of mass $80\ kg$ is standing inside a lift moving upward with a uniform velocity of $4\ m/s$. Then,the apparent weight of the person will be:

$A$ body of mass $2 \, kg$ is hung on a spring balance mounted vertically in a lift. If the lift descends with an acceleration equal to the acceleration due to gravity $g$,the reading on the spring balance will be ....... $kg$.

Two trolleys $A$ and $B$ are moving with accelerations $a$ and $2a$ respectively in the same direction. To an observer in trolley $A$,the magnitude of the pseudo force acting on a block of mass $m$ on trolley $B$ is

$A$ block of mass $m$ is kept on a wedge of mass $M$,as shown in the figure,such that mass $m$ remains stationary with respect to the wedge. The magnitude of force $P$ is

If a trolley accelerates horizontally with acceleration $a$,then the bob is displaced backward from its initial vertical position. The angular deflection of the bob in equilibrium is ..........

$A$ smooth rod of length $l$ is kept inside a trolley at an angle $\theta$ as shown in the figure. What should be the acceleration $a$ of the trolley so that the rod remains in equilibrium with respect to it?