Question

Momentum of a system of particles is conserved if:

• A. All the parties are charged
• B. When there is no external force acting on the system of the particle
• C. Few of the particles are charged
• D. All the above

Answer 1

The correct option is B When there is no external force acting on the system of the particle

We know that $F=\frac{d}{dt}P$

where $P$ is the momentum of the $system$ and $F$ is the $external$ force on the $system$ so if we put $F=0$

we will get $\frac{d}{dt}P=0$ that is $P=constant$ or $momentum$ as $conserved$ quantity.