Physics
Rotational Motion for Beginners
By Dr. Sandhya Classes Editorial Team · Published 2026-10-03 · Updated 2026-10-03 · 3 min read
Torque, moment of inertia and angular momentum explained with intuition for Class 11 and JEE.
Physics at Dr. Sandhya Classes is taught personally by Dr. Sandhya, Ph.D. in Physics, teaching since 2015 — offline in Zirakpur (Highland Marg & Lohgarh Road) and online across India. About Dr. Sandhya
Linear and rotational analogies
Displacement, velocity, force and mass have rotational partners: angle, angular velocity, torque and moment of inertia.
Moment of inertia
It depends on how mass is distributed about the axis, not only on total mass.
Rolling motion
Rolling without slipping combines translation and rotation; the contact point is momentarily at rest.
Conservation of angular momentum
With no external torque, angular momentum stays constant — explaining why a spinning skater speeds up when arms are pulled in.
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