Torque is the tendency of a force to rotate an object about an axis. It is thought to twist an object. Torque is the measure of the turning force on an object such as a bolt of a flywheel. Torque is often denoted by the Greek letter tau.

The magnitude of torque depends on three quantities: the force applied, the length or the lever arm connecting the axis to the point of force application and the angle between the force vector and the lever arm. The equations of torque are as followed:

τ=r x F

τ=rFsinθ

Where τ is the torque vector, r is the displacement vector, F is the force vector, x denotes a cross product and ϴ is the angle between the force vector and the lever arm vector. The SI unit for torque is the newton metre (Nm).