[填空题]
(a) A yo-yo is made on itpor 4pd 0r45ppakb ;e(3z*6xxbvi.4wc ft99 rd4rf two solid cylindrical 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 therxv.dr9tb6 c9xf i44w 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? %