A student briefly presses a friction pad against a rotating wheel
PHYSICS · Single correct · CBSE · Physics · System of Particles and Rotational Motion · System of Particles and Rotational Motion
Problem
A student briefly presses a friction pad against a rotating wheel, exerting a constant retarding torque of magnitude τ for a time interval Δt. Immediately after the pad is removed, the net external torque on the wheel is essentially zero. Which statement best describes the wheel’s angular momentum L during and after the contact interval?
(a) L decreases continuously both during and after the interval because the wheel continues to spin.
(b) L decreases during the interval by an amount τΔt and then remains at that new constant value afterward.
(c) L remains unchanged throughout the process because the wheel’s rotational inertia prevents any change.
(d) L increases during the interval by an amount τΔt because the applied torque adds angular momentum opposite the rotation, and then stays constant afterward.