A ball of mass 3 kg, moving with a speed of 100 ms$$^{-1}$$, strikes a wall at an angle 60$$^\circ$$ (as shown in figure). The ball rebounds at the same speed and remains in contact with the wall for 0.2 s, the force exerted by the ball on the wall 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. After the collision, if both balls move together, then the loss in kinetic energy due to collision is

A particle of mass m, moving with a velocity v makes an elastic collision in one dimension with a stationary particle of mass m. During the collision, they remain in contact with each other for an extremely small time T. Their force of contact, with time is shown in the figure. Then, F₀

The sum of moments of all the particles in a system about its centre of mass is always