[填空题]
(a) A yo-yo is made of two solid cyl :*p,a0lcm6uh -eh 5+l g8xda;yojjup indrical di w:1wyl/kij- ksks, 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 kjw1iw /k-ly:1.0-m-long string, if it is released from rest. $m/s$ (b) What fraction of its kinetic energy is rotational? %