[问答题]
A person stands, hands at hii*veld *-0czn8b cmx g.iq; hj)z2r.q s side, on a platform tha/+k/jz0gd (0bm+ :vn vk ehfptt is rotating at a rate of 1.3rev/s If he raises his arms to a horizontal position, Fig. 8–48, the speed of rotation decreases to v:/k /(kmne+vjgb zfh00dt +p 0.8 $rev/s$ (a) Why? (b) By what factor has his moment of inertia changed?