Answer: Planar (flat) bodies.
- A Planar (flat) bodies
- B All 3D bodies under usual circumstances
- C Spheres mainly
- D Hollow bodies mainly
Correct answer: A. Planar (flat) bodies
Explanation: Perpendicular axis theorem (I<sub>z</sub> = I<sub>x</sub> + I<sub>y</sub>) only applies to flat, planar (2D) objects like disks, rings, and thin rods.
Torque about axis O equals the force F multiplied by the perpendicular distance r⊥ from the axis to the line of action of the force, producing rotation.
Concept context
Moment of inertia, torque, angular momentum, rolling motion. Very high JEE weightage.
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