試題詳解

9. A record is dropped vertically onto a freely rotating (undriven) turntable. Frictional forces act to bring the record and tumntable to a common angular speed. If the rotational inertia of the record is 0.54 times that of the turntable, what percentage of the initial kinetic energy is lost?
(A) 10%
(B) 35%
(C) 18%
(D) 46%
(E) 60%.