$A$ body of mass $6\,kg$ is under a force which causes displacement in it given by $S = \frac{t^2}{4}$ metres, where $t$ is time. The work done by the force in $2\,seconds$ is ............... $J$.

$A$ particle of mass $m$ is projected at an angle $\alpha$ to the horizontal with initial velocity $u \ m/s$. What is the work done by gravity during the time it reaches its highest point?

$A$ uniform chain of length $L = 2\,m$ is kept on a table such that a length $\ell = 60\,cm$ hangs freely from the edge of the table. The total mass of the chain is $M = 4\,kg$. The work done in pulling the entire chain onto the table is ............. $J$. (Take $g = 10\,m/s^2$)

$A$ force $\vec F = (5\hat i + 3\hat j) \text{ N}$ is applied to a particle,which displaces it from its origin to the point $\vec r = (2\hat i - 1\hat j) \text{ m}$. The work done on the particle is ........... $J$.

$A$ chain of mass $m$ and length $\ell$ is held on a frictionless table in such a way that its $\frac{2 \ell}{5}$ part is hanging below the edge of the table. Find the work done to pull the hanging part of the chain up onto the table.

$A$ body of mass $m$ moves in a circle of radius $r$ with a constant speed $V$. $A$ force of $mV^2/r$ acts towards the center of the circle. Find the work done by this force when the body covers half the circumference of the circle.