[填空题]
(a) A yo-yo is made of two solid cydtj t;// /zdxulindrical d l5sfwa;ey8te.cnm9 7isks, each of mass 0.050 kg and diameter 0.075 m, join.9;e5cmywnte fal8 7sed 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 from rest. $m/s$ (b) What fraction of its kinetic energy is rotational? %