Question

An object has a momentum of 55kg*m/s and hits a stationary object making the second object starts to move. If the first object ends with a moemntum of 13kg*m/s, what is the momentum of the second object?
Momentum = p
p = mass*velocity

Answer 1

Let the moving object be object 1 and the stationary object be object 2.

Momentum of object 1 before collision = 55 kg*m/s

Momentum of object 2 before collision = 0 kg*m/s

Momentum of object 1 after collision = 13 kg*m/s

According to the law of conservation of momentum, the sum of the momenta of 2 objects remains the same even after collision. So,

Momentum of object 1 before collision + momentum of object 2 before collision = Momentum of object 1 after collision + momentum of object 2 after collision

55 + 0 = 13 + momentum of object 2 after collision

Momentum of object 2 after collision = 55 - 13 = 42 kg*m/s

Hope I helped!