This tag is for questions regarding to torque, which is a measure of the increase in angular momentum over time.
Torque, also called moment of a force, the tendency of a force to rotate the body to which it is applied. Just as force is what causes an object to accelerate in linear kinematics, torque is what causes an object to acquire angular acceleration. Hence, torque can be defined as the rotational equivalent of linear force. The point where the object rotates is called the axis of rotation.
The torque, specified with regard to the axis of rotation, is equal to the magnitude of the component of the force vector lying in the plane perpendicular to the axis, multiplied by the shortest distance between the axis and the direction of the force component.
The magnitude of the torque vector $~\tau~$ for a torque produced by a given force $~ F~$ is $$\tau =r\times F= F \cdot r \sin(\theta)~,$$ where $~r~$ is the length of the moment arm and $~\theta~$ is the angle between the force vector and the moment arm.