Newton’s first law of motion states that a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force. A free-body diagram is a drawing of all external forces acting on a body

Dynamics is the study of how forces affect the motion of objects External forces are any outside forces that act on a body.

force — a push or pull on an object with a specific magnitude and direction; can be represented by vectors; can be expressed as a multiple of a standard force. dynamics — the study of how forces affect the motion of objects and systems. free-body diagram — a sketch showing all of the external forces acting on an object or system; the system is represented by a dot, and the forces are represented by vectors extending outward from…. Newton’s first law of motion — a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force; also known as the law of inertia.