ÌâÄ¿ÄÚÈÝ
Èçͼ£¬¾ØÐÎABCDÖУ¬AB="10" cm£¬BC="6" cm£®ÏÖÓÐÁ½¸ö¶¯µãP£¬Q·Ö±ð´ÓA£¬Bͬʱ³ö·¢£¬µãPÔÚÏ߶ÎABÉÏÑØAB·½Ïò×÷ÔÈËÙÔ˶¯£¬µãQÔÚÏ߶ÎBCÉÏÑØBC·½Ïò×÷ÔÈËÙÔ˶¯£¬ÒÑÖªµãPµÄÔ˶¯ËÙ¶ÈΪ1 cm/s£¬Ô˶¯Ê±¼äΪt s£®
£¨1£©ÉèµãQµÄÔ˶¯ËÙ¶ÈΪ cm/s£®
¢Ùµ±¡÷DPQµÄÃæ»ý×îСʱ£¬ÇótµÄÖµ£»
¢Úµ±¡÷DAP¡×¡÷QBPÏàËÆʱ£¬ÇótµÄÖµ£®
£¨2£©ÉèµãQµÄÔ˶¯ËÙ¶ÈΪa cm/s£¬ÎÊÊÇ·ñ´æÔÚaµÄÖµ£¬Ê¹µÃ¡÷DAPÓë¡÷PBQºÍ¡÷QCDÕâÁ½¸öÈý½ÇÐζ¼ÏàËÆ£¿Èô´æÔÚ£¬ÇëÇó³öaµÄÖµ£»Èô²»´æÔÚ£¬Çë˵Ã÷ÀíÓÉ£®
£¨1£©ÉèµãQµÄÔ˶¯ËÙ¶ÈΪ cm/s£®
¢Ùµ±¡÷DPQµÄÃæ»ý×îСʱ£¬ÇótµÄÖµ£»
¢Úµ±¡÷DAP¡×¡÷QBPÏàËÆʱ£¬ÇótµÄÖµ£®
£¨2£©ÉèµãQµÄÔ˶¯ËÙ¶ÈΪa cm/s£¬ÎÊÊÇ·ñ´æÔÚaµÄÖµ£¬Ê¹µÃ¡÷DAPÓë¡÷PBQºÍ¡÷QCDÕâÁ½¸öÈý½ÇÐζ¼ÏàËÆ£¿Èô´æÔÚ£¬ÇëÇó³öaµÄÖµ£»Èô²»´æÔÚ£¬Çë˵Ã÷ÀíÓÉ£®
£¨1£©¢Ùt="6" ¢Út=£6£«2 £¨2£©¢Ùa=
ÊÔÌâ·ÖÎö£º£¨1£©¢ÙS¡÷DPQ=S¾ØÐÎABCD£S¡÷DAP£S¡÷PBQ£S¡÷QCD
=60£¡Á6¡Át£¡Á(10£t)¡Át£¡Á10¡Á(6£t)
=t2£3t£«30
=(t£6)2£«21£®
¡ß0¡Üt¡Ü10£¬¡àµ±t="6" sʱ£¬S¡÷DPQµÄ×îСֵΪ21 cm2£®
¢Úµ±¡÷DAP¡×¡÷QBPÏàËÆʱ£¬ÓУ®
¼´£¬½âµÃt1=£6£«2£¬t2=£6£2£¨ÉáÈ¥£©£®
¡àt=£6£«2ʱ£¬¡÷DAP¡×¡÷QBP£®
£¨2£©¼ÙÉè´æÔÚaµÄÖµ£¬Ê¹µÃ¡÷DAPÓë¡÷PBQºÍ¡÷QCDÕâÁ½¸öÈý½ÇÐζ¼ÏàËÆ£¬
ÔòAP=t£¬AQ=at£®ÒÔÏ·Ö4ÖÖÇé¿ö½øÐÐÌÖÂÛ£®
¢Ùµ±¡Ï1£½¡Ï3£½¡Ï4ʱ£¬ÓУ®
¡à£¬½âµÃt1=2£¬t2=18£¨ÉáÈ¥£©£®
´Ëʱa=£®
¢Úµ±¡Ï1£½¡Ï3£½¡Ï5ʱ£¬ÓСÏDPQ£½¡ÏPQD£½¡ÏPDQ£½90¡ã£®
´ËµÈʽ²»³ÉÁ¢£®¡à²»´æÔÚÕâÑùµÄaÖµ£®
¢Ûµ±¡Ï1£½¡Ï2£½¡Ï4ʱ£¬ÓУ®
¡à£¬¼´ÓÐÕûÀí£¬µÃ5t2£36£«180=0£¬¡÷£¼0£¬·½³ÌÎÞʵÊý½â£®
¡à²»´æÔÚÕâÑùµÄaÖµ£®
¢Üµ±¡Ï1£½¡Ï2£½¡Ï5ʱ£¬¡ßAB¡ÎDC£¬¡à¡Ï1£½¡ÏPDC£¾¡Ï5£®¹Ê²»´æÔÚÕâÑùµÄaÖµ£®
×ÛÉÏËùÊö£¬´æÔÚaµÄÖµ£¬Ê¹µÃ¡÷DAPÓë¡÷PBQºÍ¡÷QCDÕâÁ½¸öÈý½ÇÐζ¼ÏàËÆ£¬´Ëʱa=
µãÆÀ£º¸ÃÌâ·ÖÎöʱ½ÏΪ¸´ÔÓ£¬ÒÔͼÐεı߳¤ÎªÂ·³Ì£¬·ÖÎöʱ¼äµÄ±ä¶¯£¬ÒÔ¼°½ÇµÄ±ä»¯£¬Êdz£¿¼Ìâ¡£
Á·Ï°²áϵÁдð°¸
Ïà¹ØÌâÄ¿