Question

2£®Èçͼ¼×Ëùʾ£¬ÊÇijÖÖµçÈÈÒûË®»úµÄ¼ò»¯µç·ʾÒâͼ£®Í¼ÒÒÊÇËüµÄÓйزÎÊý£®ËüÓмÓÈȺͱ£ÎÂÁ½ÖÖ¹¤×÷״̬£¨ÓÉ»úÄÚοؿª¹ØS×Ô¶¯¿ØÖÆ£©£¬ÊÔÎÊ£º
£¨1£©ÒûË®»ú´¦ÓÚ±£ÎÂ״̬ʱοؿª¹ØSÓ¦´¦ÓڶϿª×´Ì¬
£¨2£©R₁ºÍR₂µÄµç×èÖµ¸÷ÊǶà´ó£¿
£¨3£©ÔÚÓõç¸ß·åÆÚ£¬¸ÃÒûË®»úµÄʵ¼Ê¹¤×÷µçѹֻÓÐ200V£¬¼ÓÈÈЧÂÊΪ80%£¬Èô½«×°ÂúË®ÏäµÄË®´Ó20¡æ¼ÓÈÈÖÁ100¡æ£¬ÐèÒª¶à³¤Ê±¼ä£¿£¨c_Ë®=4.2¡Á10³J/£¨kg¡æ£©£¬p_Ë®=1.0¡Á10³kg/m³£¬ºöÂÔζȶԵç×èµÄÓ°Ï죩

Answer 1

·ÖÎö £¨1£©·ÖÎö¿ª¹Ø±ÕºÏ£¨Ö»ÓÐR₁£©ºÍ¶Ï¿ªÊ±£¨Á½µç×è´®Áª£©µÄµç·×é³É¼°µç×è¹Øϵ£¬¸ù¾ÝP=$\frac{{U}^{2}}{R}$·ÖÎöÄÄÖÖÇé¿öµç¹¦Âʴ󣬵繦ÂÊ´óµÄΪ¼ÓÈÈ״̬£¬µç¹¦ÂÊСµÄΪ±£ÎÂ״̬£»
£¨2£©µ±¿ª¹Ø´¦ÓÚ±ÕºÏ״̬ʱ£¬ÒûË®»ú´¦ÓÚ¼ÓÈÈ״̬£¬µ±¿ª¹Ø´¦ÓڶϿª×´Ì¬Ê±£¬ÒûË®»ú´¦ÓÚ±£ÎÂ״̬£¬Óɵ繦Âʹ«Ê½µÄ±äÐι«Ê½R=$\frac{{U}^{2}}{P}$Çó³öµç×è×èÖµ£®
£¨3£©Óɵ繦Âʹ«Ê½Çó³öÈÈË®Æ÷µÄʵ¼Ê¹¦ÂÊ£¬ÓÉÈÈÁ¿¹«Ê½Çó³öË®ËùÎüÊÕµÄÈÈÁ¿£¬¸ù¾Ý¼ÓÈÈЧÂÊÇó³öÐèÒªÏûºÄµÄµçÄÜ£¬×îºóÓɹ¦Âʹ«Ê½µÄ±äÐι«Ê½Çó³ö¼ÓÈÈʱ¼ä£®

½â´ð ½â£º£¨1£©Óɵç·ͼ¿ÉÖª£¬¿ª¹ØS₀¶Ï¿ªÊ±Á½µç×è´®Áª£¬µç·µç×è½Ï´ó£¬¿ª¹ØS₀±ÕºÏʱ£¬Ö»Óеç×èR₁½ÓÈëµç·£¬µç×èR₂±»¶Ì·£¬´Ëʱµç·µç×è½ÏС£¬µçÔ´µçѹUÒ»¶¨£¬ÓÉP=$\frac{{U}^{2}}{R}$¿ÉÖª£¬µç×èÔ½´ó£¬µç·¹¦ÂÊԽС£¬µç×èԽС£¬ÒûË®»ú¹¦ÂÊÔ½´ó£¬Òò´Ëµ±¿ª¹ØS₀¶Ï¿ªÊ±£¬µç·×èÖµ½Ï´ó£¬µç¹¦ÂʽÏС£¬ÒûË®»ú´¦ÓÚ±£ÎÂ״̬£®
£¨2£©µ±¿ª¹Ø´¦ÓÚ±ÕºÏ״̬ʱ£¬ÒûË®»ú´¦ÓÚ¼ÓÈÈ״̬£¬Ö»Óеç×èR₁½ÓÈëµç·£¬
ÓÉP=$\frac{{U}^{2}}{R}$¿ÉÖª£¬µç×è×èÖµ£º
R₁=$\frac{{U}^{2}}{{P}_{¼ÓÈÈ}}$=$\frac{{£¨220V£©}^{2}}{1210W}$=40¦¸£»
R₂=$\frac{{U}^{2}}{{P}_{±£ÎÂ}}$-R₁=$\frac{{£¨220V£©}^{2}}{40W}$-40¦¸=1170¦¸£»
£¨3£©ÒûË®»ú¼ÓÈÈ״̬µÄʵ¼Ê¹¦ÂÊ£º
P_ʵ=$\frac{{U}_{ʵ¼Ê}^{2}}{{R}_{1}}$=$\frac{{£¨200V£©}^{2}}{40¦¸}$=1000W£¬
ÓɦÑ=$\frac{m}{V}$¿ÉÖª£¬Ë®µÄÖÊÁ¿£º
m=¦ÑV=1.0¡Á10³kg/m³¡Á1.5¡Á10^-3m³=1.5kg£¬
Ë®ÎüÊÕµÄÈÈÁ¿Q_Îü=cm¡÷t=4.2¡Á103J/£¨kg•¡æ£©¡Á1.5kg¡Á£¨100¡æ-20¡æ£©=5.04¡Á10⁵J
Óɹ«Ê½$\frac{{Q}_{Îü}}{¦Ç}$¦Ç=$\frac{{Q}_{Îü}}{W}$¿ÉµÃ£¬
W=$\frac{{Q}_{Îü}}{¦Ç}$=$\frac{5.04¡Á1{0}^{5}J}{80%}$=6.3¡Á10⁵J
ÓÉP=$\frac{W}{t}$¿ÉµÃ£¬¼ÓÈÈʱ¼ä£º
t=$\frac{W}{P}$=$\frac{6.3¡Á1{0}^{5}J}{1000W}$=630s£®
´ð£º£¨1£©¶Ï¿ª£»
£¨2£©R₁µÄµç×èÖµÊÇ40¦¸£¬R₁µÄµç×èÖµÊÇ1170¦¸£®
£¨3£©×°ÂúË®ÏäµÄË®´Ó20¡æ¼ÓÈÈÖÁ100¡æ£¬ÐèÒª630s£®

µãÆÀ ±¾Ì⿼²éÁ˵繦Âʹ«Ê½¡¢Ãܶȹ«Ê½¡¢ÎüÈȹ«Ê½¡¢Ð§Âʹ«Ê½¡¢µç¹¦¹«Ê½µÄ×ÛºÏÓ¦Ó㬴ÓÌâ¸ÉÖлñÈ¡ÓÐÓõÄÐÅÏ¢ÊǽâÌâµÄ¹Ø¼ü£¬¶ÔѧÉúÀ´ËµÓÐÒ»¶¨°Î¸ßÄѶȣ®