[填空题]
(a) A yo-yo is made of two solid cylinv7 r vzvfbs- fa9u.7 v:,ngfx(drical ej qp2f:zie8(disks, 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 speedez(: e2j i8pqf 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? %