Similar to continuity equations there are multiple ways to derive Navier-Stokes equation. The second law states that the rate of change of momentum of a body over time is directly proportional to the force applied and occurs in the same direction as the applied force. Derivation of Second Equation of Motion by Calculus Method.
As we know the rate of change of momentum with respect to time is proportional to the applied force.
Where F AB is an action on B while F BA is reaction of body B on A. The mathematical expression is given by F AB - F BA. F d p d t. Newtons conclusion about the magnitude of gravitational forces is summarized symbolically as.