A small object with a momentum of magnitude 5 kg*m/s approaches head-on a large object at rest. The small object bounces straight back with a momentum of magnitude 4 kg m/s. What is the magnitude of the small object's momentum change in kg m/s?
The initial momentum of the small object is 5 kg*m/s towards the larger object that is at rest. After collision, the small object bounces back with a momentum that has a magnitude or 4 kg*m/s. As the momentum of the object is now reversed it is equal to -4 kg*m/s.
The change in momentum due to the collision is initial momentum - final momentum = 5 - (-4) = 9 kg*m/s
The magnitude of change of the small object's momentum is 9 kg*m/s.