Body $A$ of mass $4m$ moving with speed $u$ collides with another body $B$ of mass $2 m$ at rest the collision is head on and elastic in nature. After the collision the fraction of energy lost by colliding body $A$ is

The total work done on a particle is equal to the change in its kinetic energy. This is applicable

A particle of mass $m$ strikes the ground inelastically, with coefficient of restitution $e$

Figure shows the vertical section of frictionless surface. A block of mass $2\, kg$ is released from the position $A$ ; its $KE$ as it reaches the position $C$ is ............ $\mathrm{J}$

A particle of mass $4\, m$ which is at rest explodes into three fragments. Two of the  fragments each of mass $m$ are found to move with a speed $v$ each in perpendicular directions. The total energy released in the process will be

A cord is used to lower vertically a block of mass $M$ by a distance $d$ with constant downward acceleration $\frac{g}{4}$. Work done by the cord on the block is