**Question**

**The velocity of a body of mass 5 kg changes from 20 m/s to 10 m/s. Calculate the change of momentum of the body.**

**[Ans : 50 kg-m/s]**

**Solution**

Mass (m) = 5 kg

Initial velocity (u) = 20 m/s

Final velocity (v) = 10 m/s

Change of momentum = m (v – u)

= 5 (10 – 20)

= 5 × (-10) = – 50 kg-m/s

The negative sign indicates that the momentum is in the opposite direction to the motion of the body.