Given that linear momentum of a system of particles is zero.

What is linear momentum ?

Is linear momentum of any system always conserved?

Define centre of mass of a system of particles.

The net external torque on a system of particles about an axis is zero. Which of the following are compatible with it?

Determine the co-ordinates of centre of mass of a system of n particles.

Two particles, each of mass mand speed v, travel in opposite directions along parallel lines separated by a distance d. Show that the vector angular momentum of the two particle system is the same whatever be the point about which the angular momentum is taken.

Does the centre of mass of a system of two particles lie on the line joining the two particles?

Prove that the time rate of change of the angular momentum of a particle is equal to the torque acting on it.