# Newton's Third Law

The third law of dynamics considers the mutual interaction between two bodies when they interact.

Definition (Third law of dynamics (or Newton's third law))

If a body A applies a force ${\displaystyle F_{A,B}}$ on the body B, the body B applies a force ${\displaystyle F_{B,A}}$ on the body A. The two forces has the same magnitude but opposite direction, so they are equal and opposed. So

${\displaystyle F_{A,B}=F_{B,A}}$

A simple example of real life in which we can clearly see the third principle of dynamics is the exhibition of two ice skaters. When one of the two pushes his partner away, not only the pushed one starts moving but also the one who pushes. That is due to the third principle of dynamics, in fact when the pusher applies a force on his partner, the partner applies an equal and opposite force on the pusher.