Power applied to a particle varies with time as $P = (4t^3 -5t + 2)\,watt$, where $t$ is in  second. Find the change is its $K.E.$ between time $t = 2$ and $t = 4 \,sec.$ ............... $\mathrm{J}$

Work done in time $t$ on a body of mass $m$ which is accelerated from rest to a speed $v$ in time $t_1$ as a function of time $t$ is given by

The force $F$ acting on a body moving in a circle of radius $r$ is always perpendicular to  the instantaneous velocity $v$. The work done by the force on the body in one complete  rotation is : 

A ball of mass $m$  is dropped from a heigh $h$  on a platform fixed at the top of a vertical spring, as shown in figure. The platform is depressed by a distance $x.$  Then the spring constant is

A particle of mass $m$ is moving in a circular path of constant radius $r$ such that its centripetal acceleration $ac$ is varying with time t as $a_c = k^2rt^2$ where $k$ is a constant. The power delivered to the particle by the force acting on it

Consider two carts, of masses $m$ and $2m$ , at rest on an air track. If you push both the carts for $3\,s$ exerting equal force on each, the kinetic energy of the light cart is