NCERT Exercise 6.12 - System of Particles and Rotational Motion
Question: A child on a frictionless turntable reduces moment of inertia to 2/5 of initial while rotating at 40 rev/min. Find new angular speed and explain energy change.
Answer: New speed = **100 rev/min**; rotational kinetic energy **increases**.
Full step-by-step NCERT solution with diagrams on Something by Zero.