Torque

Torque applied via an adjustable end wrench

Relationship between force, torque, and momentum vectors in a rotating system

In physics, torque is a turning or twisting force. If a force is used to begin to spin an object, or to stop an object from spinning, a torque is made.

The force applied to a lever, multiplied by the distance from the lever's fulcrum is described as torque.

Fulcrum

Fulcrum is the axis of rotation or point of support on which a lever turns in raising or moving something.

Equation

The equation for torque is:

$\tau = \mathbf{r}\times \mathbf{F}\,\!$

where, F is the force vector, and r is the vector from the axis of rotation to the point where the force is acting.

The SI unit of torque is the newton-metre. The most common English unit is the foot-pound.

Other websites

• "Horsepower and Torque" An article showing how power, torque, and gearing affect a vehicle's performance.
• a discussion of torque and angular momentum in an online textbook
• Torque and Angular Momentum in Circular Motion on Project PHYSNET.
• An interactive simulation of torque