Question

20£®Èçͼ£¬A¡¢BÁ½¸öÇò¾²Ö¹Óڹ⻬ˮƽ¹ìµÀ£®ÇòAµÄÖÊͯΪm₁=0£®lkg£¬BµÄÖÊÁ¿Îªm₂=0.2kg£¬ÇòB×ó²à¹Ì¶¨ÓÐÌØÊâËø¶¨¹¦ÄܵÄ΢СÇᵯ»É£¬¿ªÊ¼Ê±µ¯»É´¦ÓÚѹËõ״̬²¢±»Ëø¶¨£¬ÏÖ½â³ýµ¯»ÉµÄËø¶¨£®µ¯»É»Ö¸´µ½Ô­³¤Ê±BµÄËٶȴóСΪ3m/s£¬ÇòAÓëÊúֱǽ±ÚPÅöײºóÔ­ËÙ·µ»Ø£®¾­¹ýÒ»¶Îʱ¼äºó£¬Á½ÇòÔٴη¢ÉúÅöײ£¬µ±µ¯»ÉѹËõµ½×î¶Ìʱ£¬óʶþ´ÎËø¶¨µ¯»É£®ÒÑ֪ǽ±ÚÓÒ²à¹ìµÀ×ã¹»³¤£¬Çó£º
£¨i£©µ¯»ÉóÊÒ»´Îµ¯¿ªÊ±ÇòAµÄËٶȴóС£»
£¨ii£©µ¯»Éóʶþ´ÎËø¶¨Ê±µÄµ¯ÐÔÊÆÄÜ´óС£®

Answer 1

·ÖÎö £¨i£©µ¯»ÉóÊÒ»´Îµ¯¿ªÇòAµÃ¹ý³ÌÖУ¬AB×é³ÉµÄϵͳ¶¯Á¿Êغ㣬ÒÔÏòÓÒΪÕý£¬Óɶ¯Á¿Êغ㶨ÂÉÁÐʽÇó½â£»
£¨ii£©µ¯»Éóʶþ´ÎËø¶¨¹ý³ÌÖУ¬AB×é³ÉµÄϵͳ¶¯Á¿Êغ㣬¸ù¾Ý¶¯Á¿Êغ㶨ÂÉÒÔ¼°ÄÜÁ¿Êغ㶨ÂÉÁÐʽÇó½â¼´¿É£®

½â´ð ½â£º£¨i£©É赯»ÉóÊÒ»´Îµ¯¿ªÊ±ÇòAµÄËٶȴóСΪv₁£¬BµÄËٶȴóСΪv₂£¬µ¯¿ª¹ý³ÌÖУ¬AB×é³ÉµÄϵͳ¶¯Á¿Êغ㣬ÒÔÏòÓÒΪÕý£¬¸ù¾Ý¶¯Á¿Êغ㶨ÂÉÓУº
-m₁v₁+m₂v₂=0
½âµÃ£ºv₁=6m/s
£¨ii£©É赯»Éóʶþ´ÎËø¶¨Ê±£¬ABµÄ¹²Í¬ËÙ¶ÈΪv£¬µ¯ÐÔÊÆÄÜ´óСΪE_P£¬¸ù¾Ý¶¯Á¿Êغ㶨Âɵãº
m₁v₁+m₂v₂=£¨m₁+m₂£©v
½âµÃ£ºv=4m/s
¸ù¾ÝÄÜÁ¿Êغ㶨Âɵãº
$\frac{1}{2}{m}_{1}{{v}_{1}}^{2}+\frac{1}{2}{m}_{2}{{v}_{2}}^{2}=\frac{1}{2}£¨{m}_{1}+{m}_{2}£©{v}^{2}+{E}_{P}$
½âµÃ£ºE_P=0.3J
´ð£º£¨i£©µ¯»ÉóÊÒ»´Îµ¯¿ªÊ±ÇòAµÄËٶȴóСΪ6m/s£»
£¨ii£©µ¯»Éóʶþ´ÎËø¶¨Ê±µÄµ¯ÐÔÊÆÄÜ´óСΪ0.3J£®

µãÆÀ ½â¾ö¸ÃÌâ¹Ø¼üÒªÄܹ»ÊìÁ·ÔËÓö¯Á¿Êغ㶨ÂɺÍÄÜÁ¿Êغ㶨ÂÉÁгöµÈʽÇó½â£¬ÒªÇóͬѧÃÇÄÜÕýÈ··ÖÎöÎïÌåµÄÊÜÁ¦Çé¿ö£¬×¢ÒâʹÓö¯Á¿Êغ㶨ÂÉʱҪ¹æ¶¨Õý·½Ïò£¬ÄѶÈÊÊÖУ®