In an elastic collision of two particles the following quantity is conserved

A vertical spring with force constant $K$ is fixed on a table. A ball of mass $m$ at a height $h$ above the free upper end of the spring falls vertically on the spring so that the spring is compressed by a distance $d$. The net work done in the process is

$A$ & $B$ are blocks of same mass $m$ exactly equivalent to each other. Both are  placed on frictionless surface connected by one spring. Natural length of spring is $L$  and force constant $K$. Initially spring is in natural length. Another equivalent block $C$  of mass $m$ travelling at speed $v$ along line joining $A$ & $B$ collide with $A$. In  ideal condition maximum compression of spring is :-

If $F = 2x^2 -3x -2$, then choose correct option

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

Power applied to a particle varies with time as $P = [3t^2 -2t + 1]$ $watt$ then the change in kinetic energy of particle from $t = 2\,sec$ to $t = 4\,sec.$ ............... $\mathrm{J}$