In perfectly inelastic collisions,the relative velocity of the bodies

$A$ body of mass $m$ moving along a straight line collides with a stationary body of mass $2m$. After collision,if the two bodies move together with the same velocity,then the fraction of kinetic energy lost in the process is

Velocity of the ball $A$ after collision with the ball $B$ as shown in the figure is ............. $m/s$. (Assume perfectly inelastic and head-on collision)

$A$ mass of $20\, kg$ moving with a speed of $10\, m/s$ collides with another stationary mass of $5\, kg$. As a result of the collision,the two masses stick together. The kinetic energy of the composite mass will be ............. $J$.

$A$ block of mass $m$ moving along a straight line with constant velocity $3 \vec{V}$ collides with another block of the same mass at rest. They stick together and move with a common velocity. The common velocity is:

An object of mass $80 \,kg$ moving with velocity $2 \,ms^{-1}$ collides with another object of mass $20 \,kg$ moving with velocity $4 \,ms^{-1}$. Find the loss of energy assuming a perfectly inelastic collision. ........... $J$