Newton’s Second Law of motion states that the rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force. ie., F=ma. Where F is the force applied, m is the mass of the body, and a, the acceleration produced. If a body is subjected to multiple forces at the same time, then the acceleration produced is proportional to the vector sum (that is, the net force) of all the individual forces.
The Second Law can also relate the net force and the momentum of the body. Therefore, Newton’s Second Law also states that the net force acting on a body is equal to the rate of change of momentum of the body.