A ball $P$  collides with another identical ball  $Q$  at rest. For what value of coefficient of restitution $e$ , the  velocity of ball  $Q$  become two times that of ball  $P$  after collision

Two perfectly elastic particles $P$ and $Q$ of equal mass travelling along the line joining them with velocities $15\, m/sec$ and $10\, m/sec$. After collision, their velocities respectively (in m/sec) will be

A body starts falling freely from height $\mathrm{H}$ hits an inclined plane in its path at height $\mathrm{h}$. As a result of this perfectly elastic impact, the direction of the velocity of the body becomes horizontal. The value of $\frac{\mathrm{H}}{\mathrm{h}}$ for which the body will take the maximum time to reach the ground is______.

A body of mass $m$  moving with velocity $v$ collides head on with another body of mass $2m $ which is initially at rest. The ratio of K.E. of colliding body before and after collision will be

Two balls in free space are colliding with each other. Which of the following statement regarding linear momentum conservation of the system is true ?

A body of mass $2\, kg$ moving with a velocity of $6\, m/s$ strikes inelastically another body of same mass at rest. The amount of heat evolved during collision is ............... $\mathrm{J}$