ÌâÄ¿ÄÚÈÝ

·ÖÎö£ºÓÉÌâÎï¿é´ÓA¾²Ö¹Ï»¬£¬¼ÓËÙÖÁBÔÈËÙÖÁD£¬·ÖÎö¿ÉÖª£¬Îï¿éÔÚBD¶ÎÊܵ½µÄ»¬¶¯Ä¦²ÁÁ¦´óÓÚÔÚAB¶ÎÊܵ½µÄ»¬¶¯Ä¦²ÁÁ¦£¬Îï¿é¶ÔбÃæµÄѹÁ¦Ïàͬ£¬ËµÃ÷Îï¿éÓëAB¼äµÄ¶¯Ä¦²ÁÒòÊýСÓÚÓëBD¼äµÄ¶¯Ä¦²ÁÒòÊý£®¸ù¾Ý¶¯Äܶ¨Àí·Ö´ÓÎöÎï¿éͨ¹ýCµãµÄËÙÂÊÓëͨ¹ýBµãµÄËÙÂʵĴóС£¬ÓÉλÒƹ«Ê½x=
t·ÖÎöAB¶ÎµÄÔ˶¯Ê±¼äÓëAC¶ÎµÄÔ˶¯Ê±¼ä³¤¶Ì£®Îï¿éACEÏ»¬¹ý³Ì£¬ÏÈ×öÔȼÓËÙÔ˶¯µ½C£®´ÓCµ½E¼ÌÐø×öÔȼÓËÙÔ˶¯£¬ÓÉÓÚÊܵ½µÄ»¬¶¯Ä¦²ÁÁ¦Ôö´ó£¬CE¶ÎµÄ¼ÓËٶȱÈAC¶ÎС£®
. |
v |
½â´ð£º½â£ºAC¡¢½«Îï¿éÔÚCE¶ÎÓëBD¶ÎÔ˶¯½øÐбȽϿÉÖª£¬BD¶ÎÉÏÖØÁ¦ÑØбÃæÏòϵķÖÁ¦Ó뻬¶¯Ä¦²ÁÁ¦´óСÏàµÈ£®ÔÚCE¶ÎÉÏÖØÁ¦ÑØбÃæµÄ·ÖÁ¦½Ï´ó£¬»¬¶¯Ä¦²ÁÁ¦½ÏС£¬ÔòÖØÁ¦ÑØбÃæµÄ·ÖÁ¦´óÓÚ»¬¶¯Ä¦²ÁÁ¦£®ËùÒÔÎï¿éÑØCE¶Î½«×öÔȼÓËÙÔ˶¯£®ÓÉÉÏ·ÖÎö¿ÉÖª£¬Îï¿éÒ»Ö±¼ÓËÙÔ˶¯µ½E£¬ÓÉÓÚAC¶Î»¬¶¯Ä¦²ÁÁ¦½ÏС£¬ÔòAC¶ÎµÄ¼ÓËٶȱÈCE¶Î´ó£®¹ÊA¡¢C´íÎó£®
BD¡¢Éè¡÷ABCµÄ¸ß¶ÈΪh£¬Îï¿é»¬µ½µ½BºÍCµÄËٶȴóС·Ö±ðΪvB£¬vC£¬¶¯Ä¦²ÁÒòÊýΪ¦Ì£¬Ð±ÃæµÄÇã½ÇΪ¦Á£®¸ù¾Ý¶¯Äܶ¨ÀíµÃ£¬¶ÔAB¹ý³Ìmgh-¦Ìmgcos30¡ã?
=
mvB2£¬¶ÔAC¹ý³Ì£¬mgh-¦Ìmgcos60¡ã?
=
mvc2£®ÓÉÓÚ¦Ìmgcos30¡ã?
£¾¦Ìmgcos60¡ã?
£¬ÔòµÃµ½vB£¼vC£®ÓÉλÒƹ«Ê½µÃ xAB=
tAB£¬xAC=
tAC£¬ÒòΪxAB£¾xAC£¬vB£¼vC£¬ÔòtAB£¾tAC£®¹ÊB¡¢DÕýÈ·£®
¹ÊÑ¡BD£®
BD¡¢Éè¡÷ABCµÄ¸ß¶ÈΪh£¬Îï¿é»¬µ½µ½BºÍCµÄËٶȴóС·Ö±ðΪvB£¬vC£¬¶¯Ä¦²ÁÒòÊýΪ¦Ì£¬Ð±ÃæµÄÇã½ÇΪ¦Á£®¸ù¾Ý¶¯Äܶ¨ÀíµÃ£¬¶ÔAB¹ý³Ìmgh-¦Ìmgcos30¡ã?
h |
sin30¡ã |
1 |
2 |
h |
sin60¡ã |
1 |
2 |
h |
sin30¡ã |
h |
sin60¡ã |
vB |
2 |
vc |
2 |
¹ÊÑ¡BD£®
µãÆÀ£º±¾ÌâÊǽÏΪ¸´ÔÓµÄÔ˶¯¹ý³Ì·ÖÎöÎÊÌ⣬Ҳ¿ÉÒÔͨ¹ý×÷ËÙ¶È-ʱ¼äͼÏó½øÐзÖÎö£®

Á·Ï°²áϵÁдð°¸
Ïà¹ØÌâÄ¿