[填空题]
(a) A yo-yo is made of two solid cylindrical px, 7tv0y 7ifrd3r p ru4t iqn-ruq/uvt;:13xtisks, each of mass 0.050 kg and diameter 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 linear speed of the yo-yo when it reaches the end of its 1.0-m-long string, if it is released fro/ iqp: 4vtxqun;33tr1r uut- rm rest. $m/s$ (b) What fraction of its kinetic energy is rotational? %