Rotationsmoment

Rotationsmoment is a term found in German-language physics and engineering contexts that refers to the tendency of a force to induce rotation about a specified axis. In modern terminology, the phenomenon is usually described as torque (Drehmoment). The Rotationsmoment describes how strongly a force tends to rotate a body around a chosen pivot or axis.

Mathematically, for a force F applied at a position r relative to the rotation axis, the rotational moment is given by the cross product τ = r × F. The magnitude is |τ| = r F sin(φ), where φ is the angle between r and F. The direction of the torque is along the rotation axis, determined by the right-hand rule.

In rotational dynamics, torque relates to angular motion through τ = dL/dt, where L is the angular momentum. For a rigid body rotating about a principal axis, τ = I α, with I the moment of inertia and α the angular acceleration. In the general case, torque is a vector obtained from the inertia tensor I and the angular acceleration vector α: τ = I · α.

The SI unit of Rotationsmoment is the newton-meter (N·m). It is important to distinguish torque from work or energy; while both can be expressed in N·m, torque itself is a measure of rotational influence, not energy.

Usage and note: Rotationsmoment is largely synonymous with torque in practice, but the term is more common in older or German-language literature. In contemporary texts, Drehmoment is typically preferred, while Rotationsmoment may appear in historical discussions or translations.