What Is Torque?

Torque is the rotational analogue of force: τ = r × F, where r is the lever-arm vector from the chosen axis to the point of force application. Magnitude: τ = rF sinθ. SI unit: N·m (numerically identical to joules but conceptually different).

Newton's second law for rotation: τnet = I α, with I the moment of inertia and α the angular acceleration. The sum of torques is zero in static equilibrium; this is what lets us solve see-saw problems and structural-load distributions.

Torque depends on the choice of axis, which is also a choice. The same force can produce zero torque about an axis through its line of action and large torque about an axis far away.

Recent research on this topic from arXiv

Preprints and papers indexed on arXiv.org. Links open the public abstract pages.

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