   torque, moment, or moment of force (see the terminology below) is the tendency of a force to rotate an object about an axis,serway, r. a. and jewett, jr. j. w. (2003). physics for scientists and engineers. 6th ed. brooks cole. isbn 0-534-40842-7. fulcrum, or pivot. just as a force is a push or a pull, a torque can be thought of as a twist to an object. mathematically, torque is defined as the cross product of the lever-arm distance vector and the force vector, which tends to produce rotation. loosely speaking, torque is a measure of the turning force on an object such as a bolt or a flywheel. for example, pushing or pulling the handle of a wrench connected to a nut or bolt produces a torque (turning force) that loosens or tightens the nut or bolt. the symbol for torque is typically \tau, the greek letter tau. when it is called moment of force, it is commonly denoted m. the magnitude of torque depends on three quantities: the force applied, the length of the lever arm connecting the axis to the point of force application, and the angle between the force vector and the lever arm. in symbols: :\boldsymbol \tau = \mathbf{r}\times \mathbf{f}\,\! :\tau = \|\mathbf{r}\|\,\|\mathbf{f}\|\sin \theta\,\! where :\boldsymbol\tau is the torque vector and \tau is the magnitude of the torque, :r is the displacement vector (a vector from the point from which torque is measured to the point where force is applied), :f is the force vector, :Ã denotes the cross product, :Î¸ is the angle between the force vector and the lever arm vector. the length of the lever arm is particularly important; choosing this length appropriately lies behind the operation of levers, pulleys, gears, and most other simple machines involving a mechanical advantage. the si unit for torque is the newton metre (nÂ·m). for more on the units of torque, see units. ==terminology==  this article follows us physics terminology in its use of the word torque.physics for engineering by hendricks, subramony, and van blerk, chinappi page 148, web link in the uk and in us mechanical engineering, this is called moment of force, usually shortened to moment. in us phys
Concepts_in_physics Engine_technology Force Physical_quantities Rotation Torque