Answer
Find out the momentum of a child .
To prove
Formula
Momentum = Mass × velocity
As given
The total mass of the child and wagon is 22kg and the velocity is 1.5m/s .
Total mass = 22 kg
Velocity = 1.5 m/s
Put in the formula
Momentum = 22 × 1.5
= 33 kg- m/s
Therefore the momentum of a child and a wagon is 33 kg- m/s .