$A$ bullet hits and gets embedded in a solid block resting on a horizontal frictionless table. What is conserved?

$A$ metal ball of mass $2 \,kg$ moving with a speed of $10 \,ms^{-1}$ has a head-on collision with a stationary ball of mass $3 \,kg$. If after the collision, both the balls move together, then the loss in kinetic energy due to the collision is: (in $\,J.$)

$A$ bullet of mass $a$ and velocity $b$ is fired into a large block of mass $c$. The final velocity of the system is

In a perfectly inelastic collision,what happens to the two colliding particles after the collision?

$A$ particle of mass $m$ moving eastward with a speed $v$ collides with another particle of the same mass moving northward with the same speed $v$. The two particles coalesce on collision. The new particle of mass $2m$ will move in the north-easterly direction with a velocity

$A$ body of mass $m$ moving with velocity $v$ collides head-on with another body of mass $2m$ which is initially at rest. If the collision is perfectly inelastic,what is the loss in kinetic energy of the system?