What is the moment of a couple ? State any three characteristics of a couple . Give any one illustration for a couple.

Explanation

The product of magnitude of any one force and arm of the couple is known as moment of a couple.
Characteristics :
(1) Moment of a couple does not depend on the position of the point about which the body rotates.
(ii) A couple always produces a rotatory motion of the body.
(3) A single force cannot balance or neutralise a couple. A couple is required to balance a couple, acting on a body.
(4) If the restoring couple balances the deflecting couple, then the body is in a state of rotatory equilibrium.
Illustration of a couple
(1) openings or closing of a lid of a threaded neck of a bottle
(2) The rotation of a freely suspended magnetic needle experience a couple due to Earth's magnetic field.