Question

Name the physical quality which is expressed as moment of force.

Answer 1

Force is a vector. Moment of the force about a point is the cross (vector) product of the force and the perpendicular distance from the point to the force vector. Vector product is a vector. But the cross product of two (true) vectors gives an axial vector rather than a true vector. The axial vector behaves in the same way as a true (or polar) vector under proper transformation, but behaves differently under improper transformation.

A rotation is a proper transformation. A reflection is an improper transformation.