Two cars of equal mass $m$ moving with the same speed $v$ undergo a perfectly inelastic collision. What is the velocity of the combined mass after the collision?

$A$ particle of mass $m$ moving in the $x$-direction with speed $2v$ is hit by another particle of mass $2m$ moving in the $y$-direction with speed $v$. If the collision is perfectly inelastic,the percentage loss in the energy during the collision is close to .............. $\%$

$A$ body of mass $2 \ kg$ moving with a velocity of $6 \ m/s$ strikes inelastically another body of same mass at rest. The amount of heat evolved during collision is ............... $J$.

$A$ bullet of mass $m$ travelling with a speed $v$ hits a block of mass $M$ initially at rest and gets embedded in it. The combined system is free to move and there is no other force acting on the system. The heat generated in the process will be

$A$ bullet of mass $a$ moving with velocity $b$ strikes a block of mass $c$ and gets embedded in it. Find the velocity of the block.

$A$ bullet of mass $m$ and velocity $v$ when fired at a sand bag of mass $M$,suspended by a string,gets embedded into the bag. The loss of kinetic energy in this process is