[填空题]
(a) A yo-yo is made of tw9y mx;l:-gah3 q3i/d r:e zmlvo soug9n tv-51xmb lid 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 the linen5-m gbv t19uxar 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? %