Rigid body

A rigid body is not deformed when subjected to force or acceleration.

The pylon (left) is braced everywhere with triangles. The man below is hypnotized rigid, in a state called hypnotic catalepsy; stiff as a board.

"Hypnotic catalepsy"
The world is modeled with simplified situations. Light inextensible strings, pulleys with no friction and no moment of inertia ... and rigid bodies.