The linear momentum of a particle is conserved if and only if the net external force acting on it is zero. This means no external force is applied to change its momentum. Mathematically, the conservation of linear momentum requires that the net force on the particle be zero, so the momentum remains constant over time. In summary:
- The net external force on the particle must be zero.
- No mass change occurs in the system.
- The system is effectively closed or isolated, so internal forces cancel out and do not affect the total momentum.
Therefore, the linear momentum of a particle is conserved if the net external force acting on the particle is zero.
