Radius of gyration is defined as
1
It is the radial distance from the point to the axis of rotation where whole mass of the body is supposed to be uniformly distributed, so that the moment of inertia of system is same the given situation.
2
It is the radial distance from the point to the axis of rotation where whole mass of the body is supposed to be concentrated, so that the moment of inertia of system is same as given situation.
3
It is the Moment of inertia of a point about an axis of rotation where whole mass of the body is supposed to be concentrated, so that the moment of inertia of system is same given situation.
4
It is the moment of inertia of a point about an axis of rotation where whole mass of the body is supposed to be uniformly distributed, so that the moment of inertia of system is same as given situation.