試題詳解

6. The disk A with moment of inertia I1 rotates with angular speed ω1 about a vertical frictionless axle. A second disk B with moment of inertia I2 rotates with angular speed ω2 drops on the disk A. Since two disks are rough and two disks eventually reach the same angler speed ω, what is the final angular speed ω?
(A) (I_1ω1+ I_2ω2)/I₁
(B) (I_1ω1)/(I₁+ I₂)
(C) (I_1ω1+ I_2ω2)/( I₁+ I₂)
(D) (I_2ω2)/( I₁+ I₂)
(E) (I_1ω1− I_2ω2)/( I₁+ I₂)