The rotating or turning effect of a force about a fixed point or fixed axis

Two equal and unlike parallel forces applied simultaneously at two distinct points

Rotating effect of a couple

A circular wheel with teeth around its rim whch helps to change the speed of rotation of a wheel by changing the torque and helps to transmit power

This enables the lighter person to lift the heavier person

Torque

Couple

Moment of a couple

Gears

Seasaw