[问答题]
A person stands, hands at his side, on a platform that is rotating n.u32hngyzcx (j 2z *eat a rate *kxzmmtb-9+n of 1.3xz tnbm- *+9mkrev/s If he raises his arms to a horizontal position, Fig. 8–48, the speed of rotation decreases to 0.8 $rev/s$ (a) Why?
(b) By what factor has his moment of inertia changed?
