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.