$A$ body of mass $m_1$ moving with a uniform velocity of $40 \, m/s$ collides with another mass $m_2$ at rest,and then the two together begin to move with a uniform velocity of $30 \, m/s$. The ratio of their masses $\frac{m_1}{m_2}$ is:

$A$ body of mass $0.50 \ kg$ is moving on a smooth surface with a speed of $2.00 \ m/s$. It collides with another body of mass $1.00 \ kg$ at rest,and they move together as a single body. The energy loss during the collision is ....... $J$.

$A$ body of mass $40 \ kg$ moves with a velocity of $4 \ m/s$,and another body of mass $60 \ kg$ moves with a velocity of $2 \ m/s$. If they undergo a perfectly inelastic collision,the loss in kinetic energy is $... \ J$.

$A$ body of mass $1 \ g$ moving with a velocity of $3\hat{i} - 2\hat{j} \ m/s$ collides with a body of mass $2 \ g$ moving with a velocity of $4\hat{j} - 6\hat{k} \ m/s$. If the two bodies stick together after the collision,what is the magnitude of their combined velocity in $m/s$?

$A$ particle of mass $m$ moving with velocity $v$ collides with a stationary particle of mass $2m$. After collision,they stick together and continue to move together with velocity ........

The coefficient of restitution $e$ for a perfectly inelastic collision is