[填空题]
A 15-g lead bullet tr* krcc h4mo2l+av3fyyq wo.8og-9,mtn dbu4njdh7tj+ ;eling at $220\,m/s$ passes through a thin wall and emerges at a speed of $160\,m/s$ If the bullet absorbs 50% of the heat generated, (a) what will be the temperature rise of the bullet? (b) If the bullet’s initial temperature was 20$^{\circ} C$, will any of the bullet melt, and if so, how much? $C^{\circ} $
