Abstract:

Torque is a turning or twisting force and differs from tension which is created by a straight pull. Torque can be thought of informally as 'rotational force'.

In physics, a torque (τ) is a vector that measures the tendency of a force to rotate an object about some axis. The magnitude of a torque is defined as force times its lever arm. Just as a force is a push or a pull, a torque can be thought of as a twist.

Mathematically,

Where,

E is the energy

τ is torque

θ is the angle moved, in radians.

Relationship between torque, power and energy

If a force is allowed to act through a distance, it is doing mechanical work. Similarly, if torque is allowed to act through a rotational distance, it is doing work. Power is the work per unit time. However, time and rotational distance are related by the angular speed where each revolution results in the circumference of the circle being traveled by the force that is generating the torque. The power injected by the applied torque may be calculated as:

Conversion to other units

For different units of power, torque, or angular speed, a conversion factor must be inserted into the equation. Also, if rotational speed (revolutions per time) is used in place of angular speed (radians per time), a conversion factor of 2π must be added because there are 2π radians in a revolution:

Where rotational speed is in revolutions per unit time.