Final answer:
A lever is a simple machine that consists of a rigid bar rotating around a fixed point known as the fulcrum, which uses torques to provide mechanical advantage.
Step-by-step explanation:
The term you are looking for is a lever, which is a simple machine consisting of a rigid bar that rotates around a fixed point known as the fulcrum. This device uses the principle of torques with rotation occurring about the pivot point, and is fundamental in mechanical advantage (MA) calculations, as lever action depends greatly on the distances from the fulcrum to the points where forces are applied.
A rigid body, such as a lever or prosthetic limb in engineering, is considered ideal when it does not deform under the action of external forces and can be analyzed as a fixed, unchangeable shape. Real forces, like gravity, affect levers and dictate how they move or balance within a specific frame of reference, which can be selected based on the problem's requirements, as in the case when considering levers in equilibrium.