The person who studies motion, forces, and energy to explain how things work is typically called a physicist.

While the term "physicist" is a general term, there are also more specific terms depending on their area of specialization within physics:

* Mechanician: Focuses specifically on the mechanics of motion, forces, and energy.

* Kinematicians: Studies the motion of objects without considering the forces causing it.

* Dynamicists: Studies the motion of objects considering the forces acting upon them.

However, in most cases, "physicist" is the most common and general term used to describe someone who studies motion, forces, and energy.