Will the momentum remain conserved if some external force acts on the system ?

If no external force acts on a system

If net external force acting on the system is zero then

The velocity of centre of mass of the system remains constant, if the total external force acting on the system is.

If no external force acts on a body, it will

The momentum of a system is conserved

Select the correct alternative. When there is no external force acting on a system of particles,

Statement-1: In centre of mass frame the linear momentum of system is conserved only if no external forces are present Statement-2: In presence of external force, the centre of mass has acceleration in inertial frame equal to (Sigmavec(F)_(ext))/(m_(total))

Assertion: Linear momentum of a planet does not remain conserved. Reason: Gravitational force acts on it.