試題詳解

40. A uniform disk of mass m and radius R is rotating about its symmetric axis at an angular velocity ω₀. A ring of the same mass m and radius R originally at rest suddenly drops on the disk. Due to friction, the disk and the ring finally rotate together at a constant anular velocity ω. What is the kinetic energy loss during this process?
(A)
(B)
(C)
(D)
(E) Energy is conserved, so there is no energy loss.