Kinetics connects the physical forces applied to a mass with the resulting acceleration or change in trajectory. Unlike kinematics, which only maps the geometry of movement, this field requires calculating mass, inertia, and applied loads. Engineers use kinetic analysis to size motors, design structural supports, and predict how a mechanism will behave under real operating stresses.
We need to run a full kinetics simulation on the linkage before we spec the drive motor, since the inertial loads will spike at top dead center.
A simple memory aid is that kinetics deals with the 'why' of motion by looking at forces, while kinematics deals with the 'how' by looking only at geometry.
Related terms
Newtonian mechanics
The branch of physics that describes the motion of macroscopic bodies under the influence of forces.
Newton's second law
The principle that the force applied to a body equals its mass multiplied by its acceleration.
Motion
The collective assembly of moving parts in a complex mechanism.