ÌâÄ¿ÄÚÈÝ
ÈçͼËùʾ£¬ÓÐÒ»ÈáÈíÁ´ÌõÈ«³¤ÎªL=1.0m£¬ÖÊÁ¿·Ö²¼¾ùÔÈ£¬×ÜÖÊÁ¿ÎªM=2.0kg£¬Á´Ìõ¾ùÔÈ´øµç£¬×ܵçºÉÁ¿ÎªQ=1.0¡Á10-6C£¬½«Á´Ìõ·ÅÔÚÀëµØ×ã¹»¸ßµÄˮƽ×ÀÃæÉÏ£¬Á´ÌõÓë×À±ß´¹Ö±£¬ÇÒÒ»¶Ë¸ÕºÃÔÚ×À±ß£¬×À±ßÓй⻬»¡Ðε²°å£¬Ê¹Á´ÌõÀ뿪×À±ßºóÖ»ÄÜÊúÖ±ÏòÏÂÔ˶¯£®ÔÚˮƽ×ÀÃæµÄÉÏ·½´æÔÚÊúÖ±ÏòϵÄÔÈÇ¿µç³¡£¬µç³¡Ç¿¶ÈµÄ´óСE=2.0¡Á107V/m£®Èô×ÀÃæÓëÁ´Ìõ¼äµÄ¶¯Ä¦²ÁÒòÊýΪ¦Ì=0.5£¨ÖØÁ¦¼ÓËÙ¶ÈÈ¡10m/s2£©£¬ÊÔÇó£º
£¨1£©Á´ÌõÊܵ½µÄ×î´ó»¬¶¯Ä¦²ÁÁ¦£»
£¨2£©µ±×ÀÃæϵÄÁ´Ìõ¶à³¤Ê±£¬×ÀÃæϵÄÁ´ÌõËùÊܵ½µÄÖØÁ¦Ç¡ºÃµÈÓÚÁ´ÌõÊܵ½µÄ»¬¶¯Ä¦²ÁÁ¦£»
£¨3£©´Ó×ÀÃæÉÏ»¬ÏÂÈ«²¿Á´ÌõËùÐèµÄ×îС³õ¶¯ÄÜ£®
£¨1£©Á´ÌõÊܵ½µÄ×î´ó»¬¶¯Ä¦²ÁÁ¦£»
£¨2£©µ±×ÀÃæϵÄÁ´Ìõ¶à³¤Ê±£¬×ÀÃæϵÄÁ´ÌõËùÊܵ½µÄÖØÁ¦Ç¡ºÃµÈÓÚÁ´ÌõÊܵ½µÄ»¬¶¯Ä¦²ÁÁ¦£»
£¨3£©´Ó×ÀÃæÉÏ»¬ÏÂÈ«²¿Á´ÌõËùÐèµÄ×îС³õ¶¯ÄÜ£®
·ÖÎö£º£¨1£©×î´ó¾²Ä¦²ÁÁ¦Ô¼µÈÓÚ»¬¶¯Ä¦²ÁÁ¦£¬¸ù¾Ý»¬¶¯Ä¦²ÁÁ¦¹«Ê½¼´¿ÉÇó½â£»
£¨2£©Éè×ÀÃæϵÄÁ´Ìõ³¤Îªx£¬Á´ÌõÖÊÁ¿·Ö²¼¾ùÔÈ£¬ËùÒÔÔÚ×ÀÃæϵÄÁ´ÌõµÄÖÊÁ¿Îª
£¬Á´ÌõµÄÖØÐÄ»¹ÔÚ×ÀÃæÉÏ£¬ËùÒÔ¶Ô×À×ÓµÄѹÁ¦µÈÓÚÕû¸öÁ´ÌõµÄÖØÁ¦¼ÓÉϵ糡Á¦£¬¸ù¾ÝÁ½ÕßÏàµÈ¼´¿ÉÇó½â£»
£¨3£©µ±Á´ÌõÏ»¬0.5 mºó¾Í»á×Ô¶¯Ï»¬£¬´ËʱËÙ¶ÈÕýºÃΪÁãʱËùÐè³õ¶¯ÄÜ×îС£¬¸ù¾Ý¶¯Äܶ¨Àí¼´¿ÉÇó½â£»
£¨2£©Éè×ÀÃæϵÄÁ´Ìõ³¤Îªx£¬Á´ÌõÖÊÁ¿·Ö²¼¾ùÔÈ£¬ËùÒÔÔÚ×ÀÃæϵÄÁ´ÌõµÄÖÊÁ¿Îª
xM |
L |
£¨3£©µ±Á´ÌõÏ»¬0.5 mºó¾Í»á×Ô¶¯Ï»¬£¬´ËʱËÙ¶ÈÕýºÃΪÁãʱËùÐè³õ¶¯ÄÜ×îС£¬¸ù¾Ý¶¯Äܶ¨Àí¼´¿ÉÇó½â£»
½â´ð£º½â£º£¨1£©×î´ó¾²Ä¦²ÁÁ¦Ô¼µÈÓÚ»¬¶¯Ä¦²ÁÁ¦£¬ÔòÓУºfmax=¦Ì£¨Mg+QE£©=20 N£¬
£¨2£©Éè×ÀÃæϵÄÁ´Ìõ³¤Îªx£¬Á´ÌõÖÊÁ¿·Ö²¼¾ùÔÈ£¬ËùÒÔÔÚ×ÀÃæϵÄÁ´ÌõµÄÖÊÁ¿Îª
£¬ÔòÓУº
g=¦Ì
£¨Mg+QE£©£¬
½âµÃx=0.5 m£¬
£¨3£©Á´ÌõÏ»¬0.5 mºó¾Í»á×Ô¶¯Ï»¬£¬´ËʱËÙ¶ÈÕýºÃΪÁãʱËùÐè³õ¶¯ÄÜ×îС£¬¸ù¾Ý¶¯Äܶ¨ÀíÓУº
¡Á
-Wf=0-Ek0£¬
ÓÉÓÚfºÍN³ÉÕý±È£¬NºÍÁ´ÌõÏ»¬µÄ³¤¶È³ÉÕý±È£¬ËùÒÔfÊǾùÔȱ仯µÄ£®
¿ÉÒÔ¸ù¾Ýƽ¾ùĦ²ÁÁ¦À´ÇóWf
Wf=
?
f1ÊÇ×î³õ˲¼äµÄĦ²ÁÁ¦£¬¼´fMAX£¬ËùÒÔf1=20N
f2ÊÇÏ»¬0.5mʱµÄĦ²ÁÁ¦£¬ÓɵڶþÎʵÃÖª£¬Æä´óСµÈÓÚ°ë¸ùÁ´ÌõµÄÖØÁ¦£¬f2=10N
½âµÃ£ºEk0=Wf-
=
¡Á
-
=7.5-2.5J=5 J
´ð£º£¨1£©Á´ÌõÊܵ½µÄ×î´ó»¬¶¯Ä¦²ÁÁ¦Îª20N£»
£¨2£©µ±×ÀÃæϵÄÁ´Ìõ0.5mʱ£¬×ÀÃæϵÄÁ´ÌõËùÊܵ½µÄÖØÁ¦Ç¡ºÃµÈÓÚÁ´ÌõÊܵ½µÄ»¬¶¯Ä¦²ÁÁ¦£»
£¨3£©´Ó×ÀÃæÉÏ»¬ÏÂÈ«²¿Á´ÌõËùÐèµÄ×îС³õ¶¯ÄÜΪ5J£®
£¨2£©Éè×ÀÃæϵÄÁ´Ìõ³¤Îªx£¬Á´ÌõÖÊÁ¿·Ö²¼¾ùÔÈ£¬ËùÒÔÔÚ×ÀÃæϵÄÁ´ÌõµÄÖÊÁ¿Îª
xM |
L |
xM |
L |
L-x |
L |
½âµÃx=0.5 m£¬
£¨3£©Á´ÌõÏ»¬0.5 mºó¾Í»á×Ô¶¯Ï»¬£¬´ËʱËÙ¶ÈÕýºÃΪÁãʱËùÐè³õ¶¯ÄÜ×îС£¬¸ù¾Ý¶¯Äܶ¨ÀíÓУº
Mg |
2 |
L |
4 |
ÓÉÓÚfºÍN³ÉÕý±È£¬NºÍÁ´ÌõÏ»¬µÄ³¤¶È³ÉÕý±È£¬ËùÒÔfÊǾùÔȱ仯µÄ£®
¿ÉÒÔ¸ù¾Ýƽ¾ùĦ²ÁÁ¦À´ÇóWf
Wf=
f1+f2 |
2 |
L |
2 |
f1ÊÇ×î³õ˲¼äµÄĦ²ÁÁ¦£¬¼´fMAX£¬ËùÒÔf1=20N
f2ÊÇÏ»¬0.5mʱµÄĦ²ÁÁ¦£¬ÓɵڶþÎʵÃÖª£¬Æä´óСµÈÓÚ°ë¸ùÁ´ÌõµÄÖØÁ¦£¬f2=10N
½âµÃ£ºEk0=Wf-
MgL |
8 |
f1+f2 |
2 |
L |
2 |
MgL |
8 |
´ð£º£¨1£©Á´ÌõÊܵ½µÄ×î´ó»¬¶¯Ä¦²ÁÁ¦Îª20N£»
£¨2£©µ±×ÀÃæϵÄÁ´Ìõ0.5mʱ£¬×ÀÃæϵÄÁ´ÌõËùÊܵ½µÄÖØÁ¦Ç¡ºÃµÈÓÚÁ´ÌõÊܵ½µÄ»¬¶¯Ä¦²ÁÁ¦£»
£¨3£©´Ó×ÀÃæÉÏ»¬ÏÂÈ«²¿Á´ÌõËùÐèµÄ×îС³õ¶¯ÄÜΪ5J£®
µãÆÀ£º½â¾ö±¾ÌâÒªÖªµÀ×î´ó¾²Ä¦²ÁÁ¦Ô¼µÈÓÚ»¬¶¯Ä¦²ÁÁ¦£¬Á´ÌõÏ»¬Ò»°ëºó¾Í»á×Ô¶¯Ï»¬£¬ÄѶÈÊÊÖУ®
Á·Ï°²áϵÁдð°¸
Ïà¹ØÌâÄ¿