[填空题]
(a) A yo-yo is made of two solid cylindrical disks, each of makghu6p6 f 3(pdss 0.050 kg and 72r, j;i)xm aqap0n uodiameter 0.075 m, joined by a (concentric) thin solid cylindrical hub of mass 0.0050 kg and diameter 0.010 m. Use conservation of energy to calculate the linanim,p;0a2 )7jq orxuear speed of the yo-yo when it reaches the end of its 1.0-m-long string, if it is released from rest. $m/s$ (b) What fraction of its kinetic energy is rotational? %