JEE Main 2026 Physics question

PhysicsSystems of Particles and Rotational MotionJEE Main 2026

A solid sphere of radius 4 cm and mass 5 kg is rotating (rotation axis is passing through the centre of the sphere) with an angular velocity of 1200 rpm. It is brought to rest in 10 s by applying a constant torque. The torque applied and the number of rotations it made before it comes to rest are and respectively.

Answer: (D)

Solution

I=(2/5)(5)(0.04)²=0.0032 kg m². ω₀=1200 rpm=40π rad/s, so α=4π rad/s² and τ=Iα=0.0128π N m. Angle=ω₀t/2=200π rad, i.e. 100 rotations.

Question ID VK-015665