torsion

Torsion refers to the twisting or wrenching of an object when forces are applied to turn one part in one direction while the other part is held stationary or turned in the opposite direction. It can also describe the twisting of a bodily organ on its axis. The reactive force exerted by an elastic solid due to being twisted is also called torsion.1

A related concept is torque, which is a force that causes or tends to cause rotation or torsion. The angle of torsion, or angle of twist, is the degree to which a radial section of a body deflects from its normal position when subjected to torque.23

A torsion balance is an instrument that uses the torsion of a wire or filament to measure very small forces, such as electrostatic or magnetic attraction and repulsion. The angle of twist is proportional to the force applied. This device can also be used to measure gravitational acceleration.45