Question

3£®ÈçͼËùʾ£¬Ò»¸ö±ß³¤Îª40cmµÄÕý·½ÌåAÖØ600N£¬·ÅÔÚˮƽµØÃæÉÏ£¬²»¼ÆÉþÖغÍĦ²Á£®
£¨1£©ÒªÏëʹÈËÕ¾ÔÚµØÃæÉÏÀûÓû¬ÂÖ×齫ÖØÎïAÔÈËÙÌáÆðÀ´ÇÒÓõÄÀ­Á¦×îС£¬ÇëÔÚͼÉÏ»­³ö»¬ÂÖ×éÉÏÉþ×ÓµÄÈÆ·¨£®
£¨2£©Èç¹ûÖØÎïAÒÔ0.2m/sµÄËÙ¶ÈÔÈËÙÉÏÉý£¬È˶ÔÉþ×ÓµÄÀ­Á¦FµÄ¹¦ÂÊΪ160W£¬Ôò»¬ÂÖ×éµÄ»úеЧÂÊÊǶàÉÙ£¿
£¨3£©ÈôÓô˻¬ÂÖ×éÔÈËÙÌáÉýÁíÒ»ÎïÌåBʱ£¬»¬ÂÖ×éµÄ»úеЧÂÊΪ80%£¬ÔòÎïÌåBËùÊܵÄÖØÁ¦ÊǶàÉÙ£¿

Answer 1

·ÖÎö £¨1£©ÒªÏëʹÈËÕ¾ÔÚµØÃæÉÏÀûÓû¬ÂÖ×齫ÖØÎïAÔÈËÙÌáÆðÀ´ÇÒÓõÄÀ­Á¦×îС£¬ÔòÀ­Á¦µÄ·½ÏòÏòÏ£¬´Ó¶¨»¬ÂÖ¿ªÊ¼ÈÆÏߣ»
£¨2£©ÒÑÖªÎïÌåAÉÏÉýµÄËٶȣ¬¿ÉÒԵõ½Éþ×ÓÀ­ÏµÄËٶȣ»ÒÑÖªÀ­Á¦µÄ¹¦ÂʺÍÉþ×ÓÀ­ÏµÄËٶȣ¬¿ÉÒԵõ½À­Á¦µÄ´óС£»ÒÑÖªÀ­Á¦¡¢ÎïÖغͳе£ÎïÖصÄÉþ×Ó¶ÎÊý£¬ÀûÓæÇ=$\frac{G}{nF}$µÃµ½»¬ÂÖ×éµÄ»úеЧÂÊ£»
£¨3£©²»¼ÆÉþÖغÍĦ²Á£¬ÒÑÖªAÎïÌåµÄÎïÖغÍÊ©¼ÓµÄÀ­Á¦£¬¿ÉÒԵõ½¶¯»¬ÂÖµÄÖØÁ¦£»ÒÑÖª¶¯»¬ÂÖµÄÖØÁ¦ºÍµÚ¶þ´ÎµÄ»úеЧÂÊ£¬ÀûÓûúеЧÂʱäÐι«Ê½µÃµ½ÎïÖØB£®

½â´ð ½â£º£¨1£©ÒªÊ¹¸Ã»¬ÂÖ×éÏòÏÂÓÃÁ¦ÎïÌåÏòÉÏÔ˶¯£¬Ó¦ÏÈ´Ó¶¨»¬ÂÖ¿ªÊ¼ÈÆ£®È»ºóÒÀ´ÎÈƹý¶¯»¬ÂÖ£®ÈçÏÂͼËùʾ£º

£¨2£©Éþ×ÓÀ­ÏµÄËÙ¶ÈΪv=4v_A=4¡Á0.2m/s=0.8m/s£¬
ÓÉP=$\frac{W}{t}$=$\frac{Fs}{t}$=FvµÃ£º
Ê©¼ÓµÄÀ­Á¦Îª£º
F=$\frac{P}{v}$=$\frac{160W}{0.8m/s}$=200N£¬
»¬ÂÖ×éµÄ»úеЧÂÊΪ£º
¦Ç₁=$\frac{{W}_{ÓÐÓÃ}}{{W}_{×Ü}}$¡Á100%=$\frac{Gh}{Fs}$¡Á100=$\frac{Gh}{F4h}$¡Á100%=$\frac{{G}_{A}}{4F}$¡Á100%=$\frac{600N}{4¡Á200N}$¡Á100%=75%£»
£¨3£©ÓÉF=$\frac{1}{4}$£¨G+G_¶¯£©µÃ£º
¶¯»¬ÂÖµÄÖØÁ¦Îª£º
G_¶¯=4F-G_A=4¡Á200N-600N=200N£¬
ÒòΪ¦Ç₂=$\frac{{W}_{ÓÐÓÃ}}{{W}_{×Ü}}$=$\frac{{W}_{ÓÐÓÃ}}{{W}_{ÓÐÓÃ}+{W}_{¶î}}$=$\frac{Gh}{Gh+{G}_{¶¯}h}$=$\frac{{G}_{B}}{{G}_{B}+{G}_{¶¯}}$=80%£¬
½«G_¶¯=200N´úÈëÉÏʽ¿ÉµÃ£º$\frac{{G}_{B}}{{G}_{B}+200N}$=80%£¬
ÔòG_B£¨1-80%£©=1600N£¬
½âµÃG_B=800N£®
´ð£º£¨1£©¼ûÉÏͼ£»
£¨2£©»¬ÂÖ×éµÄ»úеЧÂÊÊÇ75%£»
£¨3£©ÎïÌåBËùÊܵÄÖØÁ¦Îª800N£®

µãÆÀ ´ËÌ⿼²éÁËÖØÁ¦µÄ¼ÆË㡢ѹǿ¼ÆË㹫ʽµÄÓ¦Óᢹ¦ÂʵļÆËã¡¢»úеЧÂʵļÆËãÒÔ¼°»¬ÂÖ×éµÄÈÆÉþ·½·¨£¬×ÛºÏÐÔ½ÏÇ¿£¬¿¼²éÁËÁ¦Ñ§Ö÷ÒªµÄ¹«Ê½»ò¹æÂÉ£¬ÓÐÒ»¶¨µÄÄѶȣ®