Concept of system

Q.

What is a system of forces?

Q.

A mass m₁ has a velocity of u and mass m₂ has a velocity of v. Then find the individual momentum of mass m₁ and mass m₂ respectively.

1. $m_{1}v$ and $m_{2}u$

2. Both have zero momentum

3. $m_{1}u$ and $m_{2}v$

4. $m_1(u+v)$ and $m_2(u+v)$