Question

12£®×Ô¶¯ÒûË®»úÒѾ­ÆÕ±éÓÃÓÚ³µÕ¾¡¢Ñ§Ð£µÈ¹«¹²³¡Ëù£¬ËüµÄ¼ò»¯µç·ͼÈçͼËùʾ£¬µçÈÈË¿µç×è·Ö±ðΪR₁¡¢R₂£®ÒÑ֪ˮµÄÃܶȦÑ_Ë®=1.0¡Á10³kg/m³£¬Ë®µÄ±ÈÈÈÈÝc_Ë®=4.2¡Á10³J/£¨kg•¡æ£©£®Çë¸ù¾Ý˵Ã÷ÊéÌṩµÄÐÅÏ¢¼ÆË㣺

ÒûË®»ú²ÎÊý

ÈÈˮζȣº¡Ý90¡æ

Èȵ¨ÈÝ»ý£º2L

¼ÓÈȶ¹¦ÂÊ£º1000W

±£Î¶¹¦ÂÊ£º40W

¶î¶¨µçѹ£º220V

ƵÂÊ£º50Hz

£¨1£©¿ª¹ØS₁¶Ï¿ªÊ±£¬ÒûË®»ú´¦ÓÚ±£ÎÂ״̬£¨Ñ¡Ìî¡°¼ÓÈÈ¡±»ò¡°±£Î¡±£©£®
£¨2£©Èç¹ûÒûË®»ú´¦ÔÚ¡°¼ÓÈÈ¡±×´Ì¬Õý³£¹¤×÷ʱ£¬µçÈÈË¿Ëù²úÉúµÄÈÈÁ¿ÓÐ80%±»Ë®ÎüÊÕ£¬ÒûË®»úµÄÈȵ¨×°ÂúË®£¬½«Ë®ÓÉ20¡æ¼ÓÈȵ½90¡æ£¬ÐèÓö೤ʱ¼ä£¿
£¨3£©µç×èË¿R₁µÄ×èÖµ£¿

Answer 1

·ÖÎö £¨1£©·ÖÎö¿ª¹ØS₁¶Ï¿ªºÍ±ÕºÏµç·µÄÁ¬½ÓÇé¿ö£¬ÓÉP=$\frac{{U}^{2}}{R}$·ÖÎö¼´¿É£»
£¨2£©ÏÈÓɦÑ=$\frac{m}{V}$¼ÆËãÈȵ¨×°ÂúË®µÄÖÊÁ¿£¬ÓÉÌâÖª£¬¦ÇW=Q£¬¸ù¾Ýµç¹¦ºÍÈÈÁ¿¹«Ê½¼ÆËã¼ÓÈÈʱ¼ä£»
£¨3£©¸ù¾Ý¼ÓÈȹ¦ÂÊÇó³öR₂µÄµç×裬¸ù¾Ý±£Î¹¦ÂÊÇó³öR₁¡¢R₂µÄ×ܵç×裬´Ó¶ø¿É¼ÆËã³öR₁µÄ×èÖµ£®

½â´ð ½â£º
£¨1£©ÓÉͼ֪£¬S₂±ÕºÏºó£¬ÈôS₁¶Ï¿ªÁ½µç×è´®Áª£¬´Ëʱµç·×ܵç×è½Ï´ó£¬ÈôS₁±ÕºÏÖ»ÓÐR₂Á¬Èëµç·£¬´Ëʱµç·Öеç×è½ÏС£®µçÔ´µçѹ²»±ä£¬ÓÉP=$\frac{{U}^{2}}{R}$¿ÉÖª£¬S₁¶Ï¿ªÊ±£¬ÒûË®»ú´¦ÓÚ±£ÎÂ״̬£»
£¨2£©Éè¼ÓÈÈËùÐèʱ¼äΪt£º
ÓɦÑ=$\frac{m}{V}$¿ÉµÃ£¬Èȵ¨ÄÚË®µÄÖÊÁ¿£º
m=¦ÑV=1.0¡Á10³kg/m³¡Á2¡Á10^-3m³=2kg£¬
ÓÉÌâÒâµÃ£¬¦ÇW=Q_Îü£¬
¼´£º¦ÇPt=cm£¨t₂-t₁£©
Ôò£ºt=$\frac{{cm£¨{t_2}-{t_1}£©}}{¦ÇP}$=$\frac{4.2¡Á1{0}^{3}J/£¨kg•¡æ£©¡Á2kg¡Á£¨90¡æ-20¡æ£©}{0.8¡Á1000W}$=735s£»
£¨3£©µ±¿ª¹Ø±ÕºÏʱ£¬R₁±»¶Ì·£¬´Ëʱ´¦ÓÚ¼ÓÈÈ״̬£¬ÓÉP=$\frac{U^2}{R}$µÃ£¬
R₂=$\frac{{U}^{2}}{{P}_{¼ÓÈÈ}}$=$\frac{£¨220V£©^{2}}{1000W}$=48.4¦¸£¬
S₁¶Ï¿ªÊ±£¬ÒûË®»ú´¦ÓÚ±£ÎÂ״̬£¬Á½µç×è´®Áª£¬ÓÉP=$\frac{U^2}{R}$µÃ£¬
R_×Ü=$\frac{{U}^{2}}{{P}_{±£ÎÂ}}$=$\frac{£¨220V£©^{2}}{40W}$=1210¦¸£¬
ÓÉ´®Áªµç·µÄµç×èÌصã¿ÉµÃ£ºR₁=R_×Ü-R₂=1210¦¸-48.4¦¸=1161.6¦¸£®
´ð£º£¨1£©±£Î£»
£¨2£©½«Ë®ÓÉ20¡æ¼ÓÈȵ½90¡æ£¬ÐèÓÃ735s£»
£¨3£©µç×èË¿R₁µÄ×èֵΪ1161.6¦¸£®

µãÆÀ ±¾ÌâÊÇÓйصçºÍÈȵÄ×ۺϼÆËãÌâÄ¿£¬»á¸ù¾Ýµç¹¦ºÍÈÈÁ¿µÄ¼ÆË㹫ʽ½øÐÐ×ۺϼÆË㣬Äܹ»¸ù¾Ýµç¹¦Âʹ«Ê½Åжϳö¼ÓÈÈ»ò±£ÎÂ״̬£¬ÀûÓúõ繦ÂʵÄÍƵ¼¹«Ê½Êǽâ¾öÎÊÌâµÄ¹Ø¼ü£®