$A$ body of mass $4\, kg$ moving with velocity $12\, m/s$ collides with another body of mass $6\, kg$ at rest. If two bodies stick together after collision,then the loss of kinetic energy of the system is .............. $J$.

$A$ bullet of mass $m$ moving horizontally with speed $v_0$ hits a wooden block of mass $M$ that is suspended from a massless string. The bullet gets lodged into the block. If the block-bullet system swings to a maximum height $h$,how much of the initial kinetic energy of the bullet is lost in the collision?

$A$ 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?

$A$ metal ball of mass $2 \ kg$ moves with a speed of $36 \ km/hr$. It collides with a stationary ball of mass $3 \ kg$. If both balls move together after the collision,the loss in kinetic energy due to the collision is ........... $J$.

$A$ mass $m$ moving horizontally (along the $x-$axis) with velocity $v$ collides and sticks to a mass of $3m$ moving vertically upward (along the $y-$axis) with velocity $2v$. The final velocity of the combination is

$A$ metal ball of mass $2 \,kg$ moving with a velocity of $36 \,km/h$ has a head-on collision with a stationary ball of mass $3 \,kg$. If after the collision,the two balls move together,the loss in kinetic energy due to the collision is ........ $J$.