Question

£¨2013·±±¾©º£µíÇø¸ßÈýÆÚÖУ¬18Ì⣩£¨10·Ö£©Èçͼ17Ëùʾ£¬ÔÚÇã½Ç¦È£½30ºµÄбÃæÉÏ·ÅÖÃÒ»¶Î°¼²ÛB£¬BÓëбÃæ¼äµÄ¶¯Ä¦²ÁÒòÊý¦Ì£½£¬²ÛÄÚ¿¿½üÓÒ²à±Ú´¦ÓÐһСÎï¿éA(¿ÉÊÓΪÖʵã)£¬Ëüµ½°¼²Û×ó²à±ÚµÄ¾àÀë

d£½0.10m¡£A¡¢BµÄÖÊÁ¿¶¼Îªm=2.0kg£¬BÓëбÃæ¼äµÄ×î´ó¾²Ä¦²ÁÁ¦¿ÉÈÏΪµÈÓÚ»¬¶¯Ä¦²ÁÁ¦£¬²»¼ÆA¡¢BÖ®¼äµÄĦ²Á£¬Ð±Ãæ×ã¹»³¤¡£ÏÖͬʱÓɾ²Ö¹ÊÍ·ÅA¡¢B£¬¾­¹ýÒ»¶Îʱ¼ä£¬AÓëBµÄ²à±Ú·¢ÉúÅöײ£¬Åöײ¹ý³Ì²»¼Æ»úеÄÜËðʧ£¬Åöײʱ¼ä¼«¶Ì¡£È¡g=10m/s²¡£Çó£º

£¨1£©Îï¿éAºÍ°¼²ÛBµÄ¼ÓËٶȷֱðÊǶà´ó£»

£¨2£©Îï¿éAÓë°¼²ÛBµÄ×ó²à±ÚµÚÒ»´ÎÅöײºó˲¼äA¡¢BµÄËٶȴóС£»

£¨3£©´Ó³õʼλÖõ½Îï¿éAÓë°¼²ÛBµÄ×ó²à±Ú·¢ÉúµÚÈý´ÎÅöײʱBµÄλÒÆ´óС¡£

Answer 1

¡¾´ð°¸¡¿¼û½âÎö

¡¾½âÎö¡¿£¨1£©ÉèAµÄ¼ÓËÙ¶ÈΪa₁£¬Ôò

mg sin=ma₁ £¬a₁= g sin¡Ásin 30¡ã=5.0m/s²¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1·Ö

ÉèBÊܵ½Ð±ÃæÊ©¼ÓµÄ»¬¶¯Ä¦²ÁÁ¦f£¬Ôò

==10N£¬·½ÏòÑØбÃæÏòÉÏ    

     BËùÊÜÖØÁ¦ÑØбÃæµÄ·ÖÁ¦=2.0¡Á10¡Ásin30¡ã=10N£¬·½ÏòÑØбÃæÏòÏÂ

ÒòΪ£¬ËùÒÔBÊÜÁ¦Æ½ºâ£¬ÊͷźóB±£³Ö¾²Ö¹£¬Ôò

°¼²ÛBµÄ¼ÓËÙ¶Èa₂=0¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1·Ö  

£¨2£©ÊÍ·ÅAºó£¬A×öÔȼÓËÙÔ˶¯£¬ÉèÎï¿éAÔ˶¯µ½°¼²ÛBµÄ×óÄÚ²à±ÚʱµÄËÙ¶ÈΪv_A0£¬¸ù¾ÝÔȱäËÙÖ±ÏßÔ˶¯¹æÂɵÃ

           

      v_A0===1.0m/s ¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1·Ö                             

ÒòA¡¢B·¢Éúµ¯ÐÔÅöײʱ¼ä¼«¶Ì£¬ÑØбÃæ·½Ïò¶¯Á¿Êغ㣬AºÍBÅöײǰºó¶¯ÄÜÊغ㣬ÉèAÓëBÅöײºóAµÄËÙ¶ÈΪv_A1£¬BµÄËÙ¶ÈΪv_B1£¬¸ù¾ÝÌâÒâÓÐ

          ¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1·Ö

     ¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1·Ö

½âµÃµÚÒ»´Î·¢ÉúÅöײºó˲¼äA¡¢BµÄËٶȷֱðΪ

v_A1=0£¬v_B1=1.0 m/s   ¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1·Ö

£¨3£©A¡¢BµÚÒ»´ÎÅöײºó£¬BÒÔv_B1=1.0 m/s×öÔÈËÙÔ˶¯£¬A×ö³õËÙ¶ÈΪ0µÄÔȼÓËÙÔ˶¯£¬Éè¾­¹ýʱ¼ät₁£¬AµÄËÙ¶Èv_A2ÓëBµÄËÙ¶ÈÏàµÈ£¬AÓëBµÄ×ó²à±Ú¾àÀë´ïµ½×î´ó£¬¼´

 v_A2=_{£¬½âµÃt1=0.20s}

Éèt₁ʱ¼äÄÚAÏ»¬µÄ¾àÀëΪx₁£¬Ôò

½âµÃx₁=0.10m

ÒòΪx₁=d£¬ ˵Ã÷AÇ¡ºÃÔ˶¯µ½BµÄÓÒ²à±Ú£¬¶øÇÒËÙ¶ÈÏàµÈ£¬ËùÒÔAÓëBµÄÓÒ²à±ÚÇ¡ºÃ½Ó´¥µ«Ã»Óз¢ÉúÅöײ¡£¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1·Ö

ÉèAÓëBµÚÒ»´ÎÅöºóµ½µÚ¶þ´ÎÅöʱËùÓÃʱ¼äΪt₂£¬ AÔ˶¯µÄ¾àÀëΪx_A1£¬BÔ˶¯µÄ¾àÀëΪx_B1£¬AµÄËÙ¶ÈΪv_A3£¬Ôò

x_A1=£¬x_B1=v_B1t₂£¬x_A1= x_B1

½âµÃt₂=0.40s £¬x_B1=0.40m£¬v_A3=a₁t₂=2.0m/s ¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1·Ö

µÚ¶þ´ÎÅöײºó£¬Óɶ¯Á¿Êغ㶨ÂɺÍÄÜÁ¿Êغ㶨ÂɿɽâµÃA¡¢BÔٴη¢ÉúËٶȽ»»»£¬BÒÔv_A3=2.0m/sËÙ¶È×öÔÈËÙÖ±ÏßÔ˶¯£¬AÒÔv_B1=1.0m/sµÄ³õËÙ¶È×öÔȼÓËÙÔ˶¯¡£

ÓÃÇ°ÃæµÚÒ»´ÎÅöײµ½µÚ¶þ´ÎÅöײµÄ·ÖÎö·½·¨¿ÉÖª£¬ÔÚºóÐøµÄÔ˶¯¹ý³ÌÖУ¬Îï¿éA²»»áÓë°¼²ÛBµÄÓÒ²à±ÚÅöײ£¬²¢ÇÒAÓëBµÚ¶þ´ÎÅöײºó£¬Ò²ÔÙ¾­¹ýt₃= 0.40s£¬AÓëB·¢ÉúµÚÈý´ÎÅöײ¡£¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1·Ö

ÉèAÓëBÔÚµÚ¶þ´ÎÅöºóµ½µÚÈý´ÎÅöʱBÔ˶¯µÄλÒÆΪx_B2£¬Ôò

   x_B2=v_A3t₃=2.0¡Á0.40=0.80m£»

Éè´Ó³õʼλÖõ½Îï¿éAÓë°¼²ÛBµÄ×óÄÚ²à±Ú·¢ÉúµÚÈý´ÎÅöײʱBµÄλÒÆ´óСx£¬Ôò

x= x_B1+ x_B2=0.40+0.80=1.2m   ¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1·Ö