ÌâÄ¿ÄÚÈÝ
ÈçͼËùʾ£¬ÖÊÁ¿Îª M = 3.0 kg µÄС³µ¾²Ö¹Ôڹ⻬µÄË®Æ½ÃæÉÏ£¬AD ²¿·ÖÊDZíÃæ´Ö²ÚµÄˮƽµ¼¹ì£¬DC ²¿·ÖÊǹ⻬µÄ
Ô²»¡µ¼¹ì£¬Õû¸öµ¼¹ìÓɾøÔµ²ÄÁÏ×ö³É²¢´¦ÓÚ B = 1.0 TµÄ´¹Ö±Ö½ÃæÏòÀïµÄÔÈÇ¿´Å³¡ÖУ¬½ñÓÐÒ»ÖÊÁ¿Îª m = 1.0 kgµÄ½ðÊô¿é£¨¿ÉÊÓΪÖʵ㣩´øµçÁ¿ q = 2.0¡Á10-3 CµÄ¸ºµç£¬ËüÒÔv0 = 8 m/s µÄËٶȳåÉÏС³µ£¬µ±Ëü½«Òª¹ý D µãʱ£¬Ëü¶Ôˮƽµ¼¹ìµÄѹÁ¦Îª 9.81 N(g È¡ 9.8 m/s2)
Ç󣺣¨1£©m´Ó A µ½ D ¹ý³ÌÖУ¬ÏµÍ³ËðʧÁ˶àÉÙ»úеÄÜ£¿
£¨2£©Èô mͨ¹ýDµãʱÁ¢¼´³·È¥´Å³¡£¬ÔÚÕâÒÔºóС³µ»ñµÃµÄ×î´óËÙ¶ÈÊǶàÉÙ£¿
![]()
£¨1£©18 J £¨2£©3 m/s
½âÎö:
£¨1£©Éè mµÖ´ïD µãµÄËÙ¶ÈΪv1 £¬Ôò£ºBqv1 +mg=N£¨2·Ö£©
¡àv1 =
=
= 5.0 m/s£¨1·Ö£©
Éè´ËС³µËÙ¶ÈΪv2£¬½ðÊô¿éÓÉ A-D ¹ý³ÌÖÐϵͳ¶¯Á¿ÊغãÔò£ºmv0 = mv1 +Mv2£¨1·Ö£© ¡àv2 = 1.0 m/s£¨1·Ö£©
¡àËðʧµÄ»úеÄܦ¤E =
mv02 -
mv12-
Mv22 = 18 J£¨2·Ö£©
£¨2£©ÔÚ m³åÉÏ
Ô²»¡ºÍ·µ»Øµ½ D µãµÄ¹ý³ÌÖУ¬Ð¡³µËÙ¶ÈÒ»Ö±ÔÚÔö´ó£¬ËùÒÔµ±½ðÊô¿é»Øµ½D µãʱС³µµÄËÙ¶È´ïµ½×î´ó£¨2·Ö£©£¬
ÇÒÔÚÉÏÊö¹ý³ÌÖÐϵͳˮƽ·½Ïò¶¯Á¿Êغ㣬Ôò£ºmv1 + Mv2 = mv1 ¡ä+Mv2¡ä£¨2·Ö£©
ϵͳ»úеÄÜÊØºã£¬Ôò£º
mv12 +
Mv22 =
mv1¡ä2+
Mv02£¨2·Ö£©
v2¡ä=1 m/sºÍv2¡ä=3 m/s£¨1·Ö£©
v2¡ä=1 m/sÉáÈ¥£¬¡àС³µÄÜ»ñµÃµÄ×î´óËÙ¶ÈΪ 3 m/s£¨1·Ö£©