Net force is the unbalanced force acting on an object. When two or more forces act on an object, the resultant vector sum of the forces is the net force
Whenever an object exerts a force on another object, the other object exerts the same amount of a force back on the first, but in the opposite direction.
Momentum is Inertia in motion. Momentum can be calculated as mass times velocity. The abbreviation for momentum is "p". A moving object can have a large momentum if it has a large mass, a high speed or both.