Question

6£®Èçͼ¼×Ëùʾ£¬ÔÚÈÝÆ÷µ×²¿¹Ì¶¨Ò»ÇáÖʵ¯»É£¬µ¯»ÉÉÏ·½Á¬ÓÐÕý·½Ìåľ¿éA£¬ÈÝÆ÷²àÃæµÄµ×²¿ÓÐÒ»¸ö·§ÃÅB£¬´Ëʱľ¿éA¸ÕºÃÍêÈ«½þûÔÚË®ÖУ¬½Ó×Å´ò¿ª·§ÃÅB£¬»ºÂý·ÅË®£¬Ö±ÖÁľ¿éAÍêÈ«À뿪ˮÃæʱ£¬Ôٹرշ§ÃÅB£¬Õâ¸ö¹ý³ÌÖУ¬µ¯»Éµ¯Á¦FÓëľ¿é¶³öË®ÃæµÄÌå»ýVµÄ¹ØϵÈçͼÒÒËùʾ£®ÒÑÖª¦Ñ_Ë®=1.0¡Á10³kg/m³£¬¦Ñ_Ë®=0.7¡Á10³kg/m³£¬Ä¾¿éÌå»ýΪV₀£¬²»¼Æµ¯»ÉËùÊܸ¡Á¦£¬ÔòÏÂÁÐ˵·¨ÕýÈ·µÄÊÇ£¨¡¡¡¡£©

• A£® µãCÓëµãEµÄ×Ý×ø±êc¡¢eµÄ¾ø¶ÔÖµÖ®±ÈΪ3£º7
• B£® Eµãʱµ¯»ÉµÄµ¯ÐÔÊÆÄܱÈCµãʱµÄµ¯ÐÔÊÆÄÜС
• C£® Dµãµ¯»É´¦ÓÚÔ­³¤£¬CD¶Îµ¯»É±»Ñ¹Ëõ
• D£® DµãµÄºá×ø±êdֵΪ0.7V₀

Answer 1

·ÖÎö £¨1£©¸ù¾ÝCµãľ¿éµÄÊÜÁ¦Çé¿öÇó³öµ¯»Éµ¯Á¦F¼´ÎªµãCµÄ×Ý×ø±êcµÄ¾ø¶ÔÖµ£»Eµãʱľ¿éAÍêÈ«À뿪ˮÃ棬´Ëʱµ¯»Éµ¯Á¦F¡äµÈÓÚľ¿éµÄÖØÁ¦£¬¼´ÎªµãEµÄ×Ý×ø±êeµÄ¾ø¶ÔÖµ£¬¶þÕßÏà±È¼´¿É£»
£¨2£©µ¯ÐÔÊÆÄܵĴóСÓ뵯ÐÔÇ¿Èõ¼°Ðαä´óСÓйأ¬¾Ý´Ë·ÖÎö£»
£¨3£©¸ù¾ÝDʱľ¿éµÄ״̬¶Ôľ¿é½øÐÐÊÜÁ¦·ÖÎö£¬½ø¶øÅжϵ¯»ÉµÄËù´¦µÄÇé¿ö£¬ÓÉͼÏó·ÖÎöDµãʱľ¿éµÄÊÜÁ¦Çé¿ö£¬ÔÙ½áºÏCµãµ¯»ÉµÄÇé¿öÀ´ÅжÏCD¶Îµ¯»ÉÊDZ»Ñ¹Ëõ»¹ÊDZ»À­É죻
£¨4£©Dµãʱ£¬Ä¾¿é´¦ÓÚƯ¸¡×´Ì¬£¬¸ù¾ÝF_¸¡=G_ľ£¬Çó³öľ¿é¶³öË®ÃæµÄÌå»ýV¼´DµãµÄºá×ø±êdµÄÖµ£®

½â´ð ½â£ºAB¡¢ÔÚCµãľ¿éÍêÈ«½þûʱ£¬Ä¾¿éÅÅ¿ªË®µÄÌå»ýV_ÅÅ=V₀£¬
´Ëʱµ¯»Éµ¯Á¦F=F_¸¡-G_ľ=¦Ñ_Ë®gV₀-¦Ñ_ľgV₀=£¨¦Ñ_Ë®-¦Ñ_ľ£©gV₀£»
ÔÚEµãľ¿éAÍêÈ«À뿪ˮÃæʱ£¬µ¯»É±»Ñ¹Ëõ£¬´Ëʱµ¯»Éµ¯Á¦µÈÓÚľ¿éµÄÖØÁ¦£¬¼´F¡ä=G_ľ=¦Ñ_ľgV₀£¬
Ôò$\frac{F}{F'}$=$\frac{£¨{¦Ñ}_{Ë®}-{¦Ñ}_{ľ}£©g{V}_{0}}{{¦Ñ}_{ľ}g{V}_{0}}$=$\frac{{¦Ñ}_{Ë®}-{¦Ñ}_{ľ}}{{¦Ñ}_{ľ}}$=$\frac{1.0¡Á1{0}^{3}kg/{m}^{3}-0.7¡Á1{0}^{3}kg/{m}^{3}}{0.7¡Á1{0}^{3}kg/{m}^{3}}$=$\frac{3}{7}$£¬¼´µãCÓëµãEµÄ×Ý×ø±êc¡¢eµÄ¾ø¶ÔÖµÖ®±ÈΪ3£º7£¬¿ÉµÃF£¼F'£¬¹ÊAÕýÈ·£¬B²»ÕýÈ·£»
C¡¢ÔÚDµãʱ£¬µ¯»Éµ¯Á¦F=0N£¬µ¯»É´¦ÓÚÔ­³¤£¬ËùÒÔCD¶Îµ¯»É±»À­É죬¹ÊC´íÎó£»
D¡¢ÔÚDµãʱ£¬µ¯»Éµ¯Á¦F=0N£¬µ¯»É´¦ÓÚÔ­³¤£¬´Ëʱľ¿éƯ¸¡ÔÚË®ÃæÉÏ£¬F_¸¡=G_ľ£¬¼´¦Ñ_Ë®gV_ÅÅ=¦Ñ_ľgV₀£¬
¦Ñ_Ë®g£¨V₀-V£©=¦Ñ_ľgV₀£¬
Ôòľ¿é¶³öË®ÃæµÄÌå»ý£º
V=£¨1-$\frac{{¦Ñ}_{ľ}}{{¦Ñ}_{Ë®}}$£©V₀=£¨1-$\frac{0.7¡Á1{0}^{3}kg/{m}^{3}}{1.0¡Á1{0}^{3}kg/{m}^{3}}$£©V₀=0.3V₀£¬
¼´DµãµÄºá×ø±êdµÄֵΪ0.3V₀£¬¹ÊD´íÎó£®
¹ÊÑ¡A£®

µãÆÀ ´ËÌ⿼²éÁËѧÉú¶Ô¸¡Á¦µÄ¼ÆËã¡¢ÎïÌ帡³ÁÌõ¼þµÄÀí½âÓëÕÆÎÕ£¬Ã÷È·µ¯»ÉÒòÊÜÁ¦²»Í¬Ðα䲻ͬºÍľ¿é½þûʱµ¯»É¶Ôľ¿éÓÐÏòϵÄÀ­Á¦¡¢Ä¾¿éÀ뿪ˮºóµ¯»É¶Ôľ¿éÓÐÏòÉϵÄÖ§³ÖÁ¦ÊÇÕýÈ·½â´ðµÄ¹Ø¼ü£®×ÜÖ®£¬´ËÌâ±È½Ï¸´ÔÓ£®