Question

ÈçͼËùʾ£¬Ë®Æ½¾øÔµ¹â»¬¹ìµÀABµÄB¶ËÓë´¦ÓÚÊúֱƽÃæÄÚµÄËÄ·ÖÖ®Ò»Ô²»¡ÐδֲھøÔµ¹ìµÀBCƽ»¬Á¬½Ó£¬Ô²»¡µÄ°ë¾¶R=0.40m¡£ÔÚ¹ìµÀËùÔÚ¿Õ¼ä´æÔÚˮƽÏòÓÒµÄÔÈÇ¿µç³¡£¬µç³¡Ç¿¶ÈE =1.0¡Á10⁴ N/C¡£ÏÖÓÐÒ»ÖÊÁ¿m=0.10kgµÄ´øµçÌ壨¿ÉÊÓΪÖʵ㣩·ÅÔÚˮƽ¹ìµÀÉÏÓëB¶Ë¾àÀës=1.0mµÄλÖã¬ÓÉÓÚÊܵ½µç³¡Á¦µÄ×÷ÓôøµçÌåÓɾ²Ö¹¿ªÊ¼Ô˶¯£¬µ±Ô˶¯µ½Ô²»¡ÐιìµÀµÄC¶Ëʱ£¬ËÙ¶ÈÇ¡ºÃΪÁã¡£ÒÑÖª´øµçÌåËù´øµçºÉq=8.0¡Á10^-5C£¬È¡g=10m/s²£¬Çó£º

£¨1£©´øµçÌåÔÚˮƽ¹ìµÀÉÏÔ˶¯µÄ¼ÓËٶȴóС¼°Ô˶¯µ½B¶ËʱµÄËٶȴóС£»
£¨2£©´øµçÌåÔ˶¯µ½Ô²»¡ÐιìµÀµÄB¶Ëʱ¶ÔÔ²»¡¹ìµÀµÄѹÁ¦´óС£»
£¨3£©´øµçÌåÑØÔ²»¡ÐιìµÀÔ˶¯¹ý³ÌÖУ¬µç³¡Á¦ºÍĦ²ÁÁ¦¶Ô´øµçÌåËù×öµÄ¹¦¸÷ÊǶàÉÙ¡£

Answer 1

£¨1£©4.0m/s£¨2£©5.0N£¨3£©-0.72J

½âÎöÊÔÌâ·ÖÎö£º£¨1£©Éè´øµçÌåÔÚˮƽ¹ìµÀÉÏÔ˶¯µÄ¼ÓËٶȴóСΪa£¬¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂÉÓÐ
qE=ma     ½âµÃ  a=qE/m=8.0m/s²¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨2·Ö£©
Éè´øµçÌåÔ˶¯µ½B¶ËµÄËٶȴóСΪv_B£¬Ôòv_B²=2as½âµÃ:  v_B==4.0m/s¡­£¨2·Ö£©
£¨2£©Éè´øµçÌåÔ˶¯µ½Ô²¹ìµÀB¶ËʱÊܹìµÀµÄÖ§³ÖÁ¦ÎªN£¬¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂÉÓÐ:
N-mg=mv_B²/R     ½âµÃ N="mg+" mv_B²/R=5.0N¡­¡­¡­¡­¡­¡­¡­¡­£¨3·Ö£©
¸ù¾ÝÅ£¶ÙµÚÈý¶¨ÂÉ¿ÉÖª£¬´øµçÌå¶ÔÔ²»¡¹ìµÀB¶ËµÄѹÁ¦´óС:N¡ä=N=5.0N¡­ £¨1·Ö£©
£¨3£©Òòµç³¡Á¦×ö¹¦Óë·¾¶Î޹أ¬ËùÒÔ´øµçÌåÑØÔ²»¡ÐιìµÀÔ˶¯¹ý³ÌÖУ¬µç³¡Á¦Ëù×öµÄ¹¦W_µç=qER=0.32J       ¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­£¨1·Ö£©
Éè´øµçÌåÑØÔ²»¡ÐιìµÀÔ˶¯¹ý³ÌÖÐĦ²ÁÁ¦Ëù×öµÄ¹¦ÎªW_Ħ£¬¶Ô´Ë¹ý³Ì¸ù¾Ý¶¯Äܶ¨ÀíÓÐ
W_µç+W_Ħ-mgR=0-mv_B²          ½âµÃ  W_Ħ=-0.72J    ¡­¡­¡­¡­£¨3·Ö£©
¿¼µã£º¿¼²éÁ¦ÓëÔ˶¯µÄ¹ØϵºÍÔ²ÖÜÔ˶¯¹æÂÉ
µãÆÀ£º±¾ÌâÄѶÈÖеȣ¬±¾Ìâ×ÛºÏÐԱȽÏÇ¿£¬¶ÔÓÚÕâÖÖ¶à¹ý³ÌÎÊÌâÒª·Ö¶Î´¦Àí£¬¶ÔÑо¿¶ÔÏó½øÐÐÊÜÁ¦·ÖÎöºÍ×ö¹¦·ÖÎö£¬¿ÉÕÒһЩÌØÊâλÖ㬶Ôij¸öλÖýøÐÐÊÜÁ¦·ÖÎö£¬ÀýÈçÔÚÔ²ÖÜÔ˶¯µÄ×î¸ßµã¾ÍÊÇÒ»¸ö³£ÀûÓõÄÌØÊâλÖÃ