ÌâÄ¿ÄÚÈÝ
ÈçͼËùʾ,Ò»¿éÖÊÁ¿ÎªM?³¤ÎªlµÄÔÈÖÊ°å·ÅÔںܳ¤µÄ¹â»¬Ë®Æ½×ÀÃæÉÏ,°åµÄ×ó¶ËÓÐÒ»ÖÊÁ¿ÎªmµÄÎï¿é,Îï¿éÉÏÁ¬½ÓÒ»¸ùºÜ³¤µÄϸÉþ,ϸÉþ¿ç¹ýλÓÚ×ÀÃæ±ßÔµµÄ¶¨»¬ÂÖ,ijÈËÒԺ㶨µÄËÙ¶ÈvÏòÏÂÀÉþ,Îï¿é×î¶àÖ»Äܵ½´ï°åµÄÖеã,¶øÇÒ´Ëʱ°åµÄÓÒ¶ËÉÐδµ½´ï×À±ß¶¨»¬ÂÖ´¦.Çó:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241424268252319.png)
(1)Îï¿éÓë°åµÄ¶¯Ä¦²ÁÒòÊý¼°Îï¿é¸Õµ½´ï°åµÄÖеãʱ°åµÄλÒÆ;
(2)Èô°åÓë×ÀÃæ¼äÓÐĦ²Á,ΪʹÎï¿éÄܵ½´ï°åµÄÓÒ¶Ë,°åÓë×ÀÃæ¼äµÄ¶¯Ä¦²ÁÒòÊýµÄ·¶Î§;
(3)Èô°åÓë×ÀÃæ¼äµÄ¶¯Ä¦²ÁÒòÊýÈ¡(2)ÎÊÖеÄ×îСֵ,ÔÚÎï¿é´Ó°åµÄ×ó¶ËÔ˶¯µ½ÓҶ˵Ĺý³ÌÖÐ,ÈËÀÉþµÄÁ¦Ëù×öµÄ¹¦(ÆäËû×èÁ¦¾ù²»¼Æ).
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241424268252319.png)
(1)Îï¿éÓë°åµÄ¶¯Ä¦²ÁÒòÊý¼°Îï¿é¸Õµ½´ï°åµÄÖеãʱ°åµÄλÒÆ;
(2)Èô°åÓë×ÀÃæ¼äÓÐĦ²Á,ΪʹÎï¿éÄܵ½´ï°åµÄÓÒ¶Ë,°åÓë×ÀÃæ¼äµÄ¶¯Ä¦²ÁÒòÊýµÄ·¶Î§;
(3)Èô°åÓë×ÀÃæ¼äµÄ¶¯Ä¦²ÁÒòÊýÈ¡(2)ÎÊÖеÄ×îСֵ,ÔÚÎï¿é´Ó°åµÄ×ó¶ËÔ˶¯µ½ÓҶ˵Ĺý³ÌÖÐ,ÈËÀÉþµÄÁ¦Ëù×öµÄ¹¦(ÆäËû×èÁ¦¾ù²»¼Æ).
(1)
(2)´óÓÚ
(3)2Mv2
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142426935900.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142426981998.png)
(1)ÉèÎï¿éÔÚ°åÉÏ»¬ÐеÄʱ¼äΪt1,¶Ô°åÓ¦Óö¯Á¿¶¨ÀíµÃ:
¦Ì1mgt1=Mv,t1=
¢Ù
ÉèÔڴ˹ý³ÌÖÐÎï¿éÇ°½øλÒÆΪs1,°åǰλÒÆΪs2,
Ôòs1=v¡¤t1 ¢Ú
s2=
t1 ¢Û
s1-s2=
¢Ü
ÓÉ¢Ù~¢ÜµÃÎï¿éÓë°å¼äµÄ¶¯Ä¦²ÁÒòÊýΪ¦Ì1=
°åµÄλÒÆs2=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142427356408.png)
(2)Éè°åÓë×ÀÃæ¼äµÄ¶¯Ä¦²ÁÒòÊýΪ¦Ì2,Îï¿éÔÚ°åÉÏ»¬ÐеÄʱ¼äΪt2.ÔòÓ¦Óö¯Á¿¶¨ÀíµÃ
[¦Ì1mg-¦Ì2(m+M)g]¡¤t2=Mv,
t2=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241424275121101.png)
ÓÖÉèÎï¿é´Ó°åµÄ×ó¶ËÔ˶¯µ½ÓҶ˵Äʱ¼äΪt3
Ôò
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142428105990.png)
ΪÁËʹÎï¿éÄܵ½´ï°åµÄÓÒ¶Ë,±ØÐëÂú×ãt2¡Ýt3
¼´
¡Ý
,¦Ì2¡Ý![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241424283391003.png)
ËùÒÔΪÁËʹÎï¿éÄܵ½´ï°åµÄÓÒ¶Ë,Ӧʹ°åÓë×ÀÃæµÄ¶¯Ä¦²ÁÒòÊý¦Ì2¡Ý![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241424283391003.png)
(3)ÉèÉþ×ÓµÄÀÁ¦ÎªT,Îï¿é´Ó°åµÄ×ó¶Ëµ½´ïÓҶ˵Ĺý³ÌÖÐÎï¿éµÄλÒÆΪs3,ÔòÓÐ:T-¦Ì1mg=0,s3=v¡¤t3=2l
Óɹ¦µÄ¼ÆË㹫ʽµÃ:WT=T¡¤s3=¦Ì1mg¡¤2l=
¡¤mg¡¤2l=2Mv2
ËùÒÔÉþµÄÀÁ¦×ö¹¦Îª2Mv2.
(»òW=¦¤Ek+Q1+Q2=
Mv2+¦Ì1mgl+¦Ì2(M+m)gl=2Mv2)
¦Ì1mgt1=Mv,t1=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142427059743.png)
ÉèÔڴ˹ý³ÌÖÐÎï¿éÇ°½øλÒÆΪs1,°åǰλÒÆΪs2,
Ôòs1=v¡¤t1 ¢Ú
s2=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142427122393.png)
s1-s2=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142427184398.png)
ÓÉ¢Ù~¢ÜµÃÎï¿éÓë°å¼äµÄ¶¯Ä¦²ÁÒòÊýΪ¦Ì1=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142427262779.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142427356408.png)
(2)Éè°åÓë×ÀÃæ¼äµÄ¶¯Ä¦²ÁÒòÊýΪ¦Ì2,Îï¿éÔÚ°åÉÏ»¬ÐеÄʱ¼äΪt2.ÔòÓ¦Óö¯Á¿¶¨ÀíµÃ
[¦Ì1mg-¦Ì2(m+M)g]¡¤t2=Mv,
t2=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241424275121101.png)
ÓÖÉèÎï¿é´Ó°åµÄ×ó¶ËÔ˶¯µ½ÓҶ˵Äʱ¼äΪt3
Ôò
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142428105990.png)
ΪÁËʹÎï¿éÄܵ½´ï°åµÄÓÒ¶Ë,±ØÐëÂú×ãt2¡Ýt3
¼´
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241424275121101.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142428261461.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241424283391003.png)
ËùÒÔΪÁËʹÎï¿éÄܵ½´ï°åµÄÓÒ¶Ë,Ӧʹ°åÓë×ÀÃæµÄ¶¯Ä¦²ÁÒòÊý¦Ì2¡Ý
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241424283391003.png)
(3)ÉèÉþ×ÓµÄÀÁ¦ÎªT,Îï¿é´Ó°åµÄ×ó¶Ëµ½´ïÓҶ˵Ĺý³ÌÖÐÎï¿éµÄλÒÆΪs3,ÔòÓÐ:T-¦Ì1mg=0,s3=v¡¤t3=2l
Óɹ¦µÄ¼ÆË㹫ʽµÃ:WT=T¡¤s3=¦Ì1mg¡¤2l=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142428479751.png)
ËùÒÔÉþµÄÀÁ¦×ö¹¦Îª2Mv2.
(»òW=¦¤Ek+Q1+Q2=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824142428651338.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
Á·Ï°²áϵÁдð°¸
Ïà¹ØÌâÄ¿