$A$ body of mass $m_1$ undergoes a perfectly elastic collision with a stationary body of mass $m_2$. If the velocity of mass $m_1$ becomes $1/1.5$ times its initial velocity,find the ratio $\frac{m_1}{m_2}$.

$A$ heavy body moving with a velocity $30\, m/s$ and another small object at rest undergo an elastic collision. The latter will move with a velocity of .............. $m/s$.

$A$ particle of mass $m_1$ collides with a particle of mass $m_2$ at rest. After the elastic collision,the two particles move at an angle of $90^{\circ}$ with respect to each other. The ratio $\frac{m_2}{m_1}$ is

$A$ light particle moving horizontally with a speed $v_1$ strikes a very heavy block moving in the same direction with a speed $v_2$. The collision is elastic. After the collision,the velocity of the particle is:

$A$ body of mass $30 \ kg$ moving with a velocity $20 \ ms^{-1}$ undergoes a one-dimensional elastic collision with another ball of the same mass moving in the opposite direction with a velocity of $30 \ ms^{-1}$. After the collision,the velocities of the first and second bodies respectively are:

$A$ particle of mass $m$ collides with a heavy mass $M$ (initially at rest) elastically. After the collision, the particle returns with $4/9$ of its initial kinetic energy. The mass of the heavy object $M$ is ............... $m$.