Question

£¨08ÄêºþÄÏʦ´ó¸½ÖÐÔ¿¼£©£¨16·Ö£©ÈçͼËùʾ£¬CÊÇ·ÅÔڹ⻬µÄˮƽÃæÉϵÄÒ»¿éľ°å£¬Ä¾°åµÄÖÊÁ¿Îª3m£¬ÔÚľ°åµÄÉÏÃæÓÐÁ½¿éÖÊÁ¿¾ùΪmµÄСľ¿éAºÍB£¬ËüÃÇÓëľ°å¼äµÄ¶¯Ä¦²ÁÒòÊý¾ùΪ¦Ì.×î³õľ°å¾²Ö¹£¬A¡¢BÁ½Ä¾¿éͬʱÒÔ·½ÏòˮƽÏòÓҵijõËÙ¶Èv₀ºÍ2v₀ÔÚľ°åÉÏ»¬¶¯£¬Ä¾°å×ã¹»³¤£¬A¡¢BʼÖÕ们Àëľ°å.Çó£º

£¨1£©Ä¾¿éB´Ó¸Õ¿ªÊ¼Ô˶¯µ½Óëľ°åCËٶȸպÃÏàµÈµÄ¹ý³ÌÖУ¬Ä¾¿éBËù·¢ÉúµÄλÒÆ£»

£¨2£©Ä¾¿éAÔÚÕû¸ö¹ý³ÌÖеÄ×îСËٶȣ»

£¨3£©Õû¸ö¹ý³ÌÖУ¬A¡¢BÁ½Ä¾¿éÏà¶ÔÓÚ»¬°å»¬¶¯µÄ×Ü·³ÌÊǶàÉÙ£¿

Answer 1

£¨1£©Ä¾¿éAÏÈ×öÔȼõËÙÖ±ÏßÔ˶¯£¬ºó×öÔȼÓËÙÖ±ÏßÔ˶¯£»Ä¾¿éBÒ»Ö±×öÔȼõËÙÖ±ÏßÔ˶¯£»Ä¾°åC×öÁ½¶Î¼ÓËٶȲ»Í¬µÄÔȼÓËÙÖ±ÏßÔ˶¯£¬Ö±µ½A¡¢B¡¢CÈýÕßµÄËÙ¶ÈÏàµÈΪֹ£¬ÉèΪv₁.¶ÔA¡¢B¡¢CÈýÕß×é³ÉµÄϵͳ£¬Óɶ¯Á¿Êغ㶨Âɵãº

mv₀+2mv₀=(m+m+3m)v₁¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨2·Ö£©

 

½âµÃ£ºv₁=0.6 v₀

 

¶Ôľ¿éBÔËÓö¯Äܶ¨Àí£¬ÓУº

 

-¦Ìmgs=¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨2·Ö£©

 

½âµÃ£ºs=91/(50¦Ìg)¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨2·Ö£©

 

£¨2£©Éèľ¿éAÔÚÕû¸ö¹ý³ÌÖеÄ×îСËÙ¶ÈΪv¡ä£¬ËùÓÃʱ¼äΪt£¬ÓÉÅ£¶ÙµÚ¶þ¶¨ÂÉ£º

 

¶Ôľ¿éA£ºa₁=¦Ìmg/m=¦Ìg£¬¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨1·Ö£©

¶Ôľ¿éC£ºa₂=2¦Ìmg/3m=2¦Ìg/3£¬¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨1·Ö£©

 

µ±Ä¾¿éAÓëľ°åCµÄËÙ¶ÈÏàµÈʱ£¬Ä¾¿éAµÄËÙ¶È×îС£¬Òò´ËÓУº

 

v₀-¦Ìgt=(2¦Ìg/3)t¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨1·Ö£©

 

½âµÃt=3v₀/(5¦Ìg)¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨1·Ö£©

 

ľ¿éAÔÚÕû¸ö¹ý³ÌÖеÄ×îСËÙ¶ÈΪ£ºv¡ä=v₀-a₁t=2v₀ /5.¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨2·Ö£©

 

£¨3£©Q_×Ü=Q₁+Q₂ = fs_Ïà1+fs_Ïà2=¦¤E_kËð¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨2·Ö£©

 

ËùÒÔs_Ïà×Ü=s_Ïà1+s_Ïà2=¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨2·Ö£©