Four solid rigid balls reach of mass m and radius r are fixed on a rigid-ring of radius 2r and mass 2m. The system is whirled about 'O' as shown. The radius of gyration of the system is :

Four rings each of mass M and radius R are arranged as shown in the figure. The moment of inertia of the system about YY' will be

Four rings each of mass M and radius R are arranged as shown in the figure. The moment of inertia of the system about YY' will be

Three rings each of mass M and radius R are placed in contact with each other as shown . Then MI of the system about YY' axis is

Three rings each of mass m and radius r are so placed that they touch each other. The radius of gyration of the system about the axis as shown in the figure is

Three rings each of mass m and radius r are so placed that they touch each other. The radius of gyration of the system about the axis as shown in the figure is

Two rings of same mass and radius R are placed with their planes perpendicular to each other and centre at a common point. The radius of gyration of the system about an axis passing through the centre and perpendicular to the plane of one ring is

Two rings of same mass and radius R are placed with their planes perpendicular to each other and centre at a common point. The radius of gyration of the system about an axis passing through the centre and perpendicular to the plane of one ring is

Three rings each of mass M and radius R are arranged as shown in the figure. The moment of inertia of the system about YY¢ will be