[问答题]
A person stands, hanhxzrj+c+y :c y+c .jo.ds at hiui3c6t m3v 3ybs side, on a platform that is rotating at a rate of 1.3rev/s 3m3tc6uibv 3 yIf 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?
