Question

why newton 3rd law differ from newton 2nd law why????

Answer 1

The second law is about how one object responds to the forces acting ON it. ... Or The net force required to accelerate a Body (of mass 'm') to an acceleration 'a', would be 'ma'. Whereas in the third law Newton was talking about interaction between two bodies. It says that every Action has an equal and opposite reaction.

Answer 2

Because in second law we know that in it there is product of mass and velocity and difrence between intial and final momentum in time taken called as rate of change momentum but in third law action and reaction , intial momentum of both and final momentum of both is equal after collsion