The study of forces acting on bodies whether at rest or in motion is called Dynamics.

Here's a breakdown:

* Dynamics is a branch of physics that deals with the study of motion and its causes.

* It explores the relationship between forces, mass, and motion.

* Statics is a subfield of dynamics that specifically focuses on bodies at rest, where the net force acting on the object is zero.

* Kinematics is another subfield of dynamics that deals with the description of motion, without considering the forces causing it.

So, while the study of forces is a core element of dynamics, it encompasses both bodies at rest and in motion.