Question

The parallel axis theorem can be applied to

• A. Any two parallel axes
• B. Any two parallel axes of which one must lie within the body
• C. Any two parallel axes of which one must pass through the centre of mass of the body
• D. Any two parallel axes lying in the plane of the body

Answer 1

The correct option is C Any two parallel axes of which one must pass through the centre of mass of the body

As parallel theorem states that the moment of inertia of a planar body about an axis parallel to an axis passing through the center of mass is equal to the sum of the moment of inertia of body about an axis passing through center of mass and product of mass & square of the distance between two axes.

$I_z=I_{cm}+M{R}_d^2$

Hence, any of two parallel axes of which one must pass through the center of mass of the body.