⚛️ Physics · System of Particles and Rotational Motion · NEET & JEE

A turntable rotating at 60 rpm has moment of inertia 4 kg·m². A person of mass 60 kg sits at the edge (r = 1 m). What is the new angular velocity? (Assume no friction)

Answer: 60π/32 rad/s.

A 60π/32 rad/s
B 2π rad/s
C 60π rad/s
D π/2 rad/s

Correct answer: A. 60π/32 rad/s

Explanation: L conserved: Iω = (I + mr²)ω'. ω_i = 2π rad/s. 4 × 2π = (4+60)ω' → ω' = 8π/64 = π/8 rad/s.

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.

Read the full System of Particles and Rotational Motion notes →

A turntable rotating at 60 rpm has moment of inertia 4 kg·m². A person of mass 60 kg sits at the edge (r = 1 m). What is the new angular velocity? (Assume no friction)

Concept context

More System of Particles and Rotational Motion questions