When two bodies stick together after collision,the collision is said to be

$A$ particle of mass $m_1$ undergoes a perfectly inelastic head-on collision with another particle of mass $m_2$ at rest $(m_2 > m_1)$. What fraction of the initial kinetic energy is converted into heat energy during this collision?

$A$ body of mass $5\,kg$ strikes another body of mass $2.5\,kg$ initially at rest. The bodies after collision coalesce and begin to move as a whole with a kinetic energy of $5\,J$. The kinetic energy of the first body before collision is ............... $J$.

$A$ particle of mass $m$ moves with velocity $v$ towards the East. It collides with another particle of the same mass and same speed moving towards the North and sticks to it. What will be the velocity of the combined particles?

Two identical masses $M$ moving with velocities $\mu_1$ and $\mu_2$ collide perfectly inelastically. The loss in energy is

$A$ body of mass $2\, kg$ moving with a velocity of $3\, m/s$ collides head-on with a body of mass $1\, kg$ moving in the opposite direction with a velocity of $4\, m/s$. After the collision,the two bodies stick together and move with a common velocity. The common velocity in $m/s$ is equal to: