What will be the total linear momentum of a system of particles in a rotatory motion ?

Two particles of mass 2kg and 6kg are moving on smooth horizontal surface collides with each other.If velocity of their common centre of mass is 10m/s before collision then what will be the total linear momentum of system of particles after collision.(Assume they move along the surface after collision)

The angular momentum of a system of particles is conserved

What are the units of linear momentum?

Show that the total linear momentum of a system of particles is conserved in the absence of any external force. Also show that total linear momentum of the system is equal to the product of the total mass of the system and the velocity of its centre of mass.

Prove that the rate of change of total angular momentum of a system of particles is equal to the total torque acting on the system.

Angular momentum of the system of particles changes when

Total linear momentum of a system of particles is equal to ……………..of the system and velocity of ……… .