State Newton's 2nd law of motion.
The second law of notion states that the rate of change of momentum of a body is directly proportional to the unbalanced external force acting on it.
Let a force $$F$$ is acting on a body. Due to the force, the momentum of the body changes by $$\Delta P$$ in time $$\Delta t$$.
The rate of change of momentum = $$\dfrac{\Delta P}{\Delta t}$$
According to Newton's second law of motion: $$F\propto \dfrac{\Delta p}{\Delta t}$$