$A$ point mass $m$ is suspended from a light thread of length $l$,fixed at $O$,and is whirled in a horizontal circle at a constant speed as shown. From your point of view,stationary with respect to the mass,the forces on the mass are

$A$ man of weight $W$ is standing on a lift which is moving downward with an acceleration $a$. The apparent weight of the man is

$A$ box of mass $m \, kg$ is placed on the rear side of an open truck accelerating at $4 \, m/s^2$. The coefficient of friction between the box and the surface below it is $0.4$. The net acceleration of the box with respect to the truck is zero. The value of $m$ is :- $[g = 10 \, m/s^2]$

$A$ vessel containing water is moving with a constant speed towards the right along a straight horizontal path. If the vessel is given a constant retardation towards the right along a straight line,which of the following diagrams represents the surface of the liquid?

$A$ wooden block of mass $5 \, kg$ rests on a soft horizontal floor. When an iron cylinder of mass $25 \, kg$ is placed on top of the block, the floor yields and the block and the cylinder together move down with an acceleration of $0.1 \, m/s^2$. The action force of the system on the floor is equal to: (in $N$)

In the figure shown,$P$ is a plate on which a wedge $B$ is placed,and on $B$ a block $A$ of mass $m$ is placed. The plate is suddenly removed and the system of $B$ and $A$ is allowed to fall under gravity. Neglecting any force due to air on $A$ and $B$,the normal force on $A$ due to $B$ is