A truck moving on horizontal road towards east with velocity $20\, ms^{-1}$ collides elastically with a light ball moving with velocity $25\, ms^{-1}$ along west. The velocity of the ball just after collision

A body falling from a height of $10\,m$ rebounds from hard floor. If it loses $20\%$ energy in the impact, then coefficient of restitution is

A body of mass $4\  kg$ collides head-on elastically with another body of mass $2\  kg$ kept at rest in free space. Time of collision is $0.02\  sec$ and average impulse force acted on each bodies is $100\  N$. Find the velocity of the $2\  kg$ body after the impact

A ball of mass $m$ suspended from a rigid support by an inextensible massless string is released from a height $h$ above its lowest point. At its lowest point, it collides elastically with a block of mass $2 m$ at rest on a frictionless surface. Neglect the dimensions of the ball and the block. After the collision, the ball rises to a maximum height of

A smooth rightangled wedge of mass $M$ is kept on a smooth horizontal surface as shown. A mass $m$ is released from top of wedge when $m$ reaches ground its speed is $V$. Work done by normal contact force on $m$, while it comes down to ground is :-

Consider elastic collision of a particle of mass $m $ moving with a velocity $u$ with another particle of the same mass at rest. After the collision the projectile and the struck particle move in directions making angles ${\theta _1}$and ${\theta _2}$respectively with the initial direction of motion. The sum of the angles. ${\theta _1} + {\theta _2},$ is......$^o$