Question

19£®ÀûÓÃÈçͼËùʾµÄ»¬ÂÖ×飬½«ÖØ800NµÄÎïÌå10sÊúÖ±ÏòÉÏÔÈËÙÌáÉý1m£¬¹¤È˶ÔÉþµÄÀ­Á¦Îª500N£¬Èô²»¼ÆÉþÖغÍĦ²Á£¬ÔòÓйػ¬ÂÖ×éµÄÏÂÁÐ˵·¨ÕýÈ·µÄÊÇ£¨¡¡¡¡£©

• A£® ¶¯»¬ÂÖÖØΪ100N£¬»¬ÂÖ×é»úеЧÂÊΪ80%
• B£® ¶¯»¬ÂÖÖØΪ200N£¬À­Á¦µÄ¹¦ÂÊΪ100W
• C£® Óô˻¬ÂÖ×éÌáÆð1000NµÄÎïÌåʱ»¬ÂÖ×é»úеЧÂÊ»áÔö¼Ó
• D£® Éþ×Ó×ÔÓɶËÒƶ¯µÄËÙ¶ÈΪ0.1m/s£¬»¬ÂÖ×é»úеЧÂÊΪ62.5%

Answer 1

·ÖÎö £¨1£©ÓÉͼ¿É֪ʹÓû¬ÂÖ×é³Ðµ£ÎïÖصÄÉþ×Ó¹ÉÊýn=2£¬²»¼ÆÉþÖغÍĦ²Á£¬À­Á¦F=$\frac{1}{2}$£¨G+G_¶¯£©£¬¾Ý´ËÇ󶯻¬ÂÖµÄÖØÁ¦£»
£¨2£©Éþ¶ËÒƶ¯µÄ¾àÀës=2h£¬ÀûÓÃËٶȹ«Ê½ÇóÉþ×Ó×ÔÓɶËÔ˶¯µÄËٶȣ»
£¨3£©ÀûÓÃW=FsÇóÀ­Á¦×öµÄ×ܹ¦£¬ÔÙÀûÓÃP=$\frac{W}{t}$ÇóÀ­Á¦µÄ¹¦ÂÊ£»
£¨4£©ÀûÓÃW=GhÇóÓÐÓù¦£¬ÔÙÀûÓÃЧÂʹ«Ê½Çó¸Ã»¬ÂÖ×éµÄ»úеЧÂÊ£»
£¨5£©Ìá¸ß»¬ÂÖ×é»úеЧÂʵķ½·¨£ºÒ»ÊÇÔö´óÌáÉýµÄÎïÖØ£¬¶þÊǼõСĦ²Á¡¢¼õÇᶯ»¬ÂÖÖØÁ¦£®

½â´ð ½â£º£¨1£©ÓÉͼ¿ÉÖª£¬n=2£¬
²»¼ÆÉþÖغÍĦ²Á£¬À­Á¦F=$\frac{1}{2}$£¨G+G_¶¯£©¿ÉµÃ£¬¶¯»¬ÂÖµÄÖØÁ¦£º
G_¶¯=2F-G=2¡Á500N-800N=200N£»
£¨2£©Éþ¶ËÒƶ¯µÄ¾àÀës=2h=2¡Á1m=2m£¬
Éþ×Ó×ÔÓɶËÔ˶¯µÄËٶȣºv=$\frac{s}{t}$=$\frac{2m}{10s}$=0.2m/s£»
£¨3£©À­Á¦×öµÄ×ܹ¦W_×Ü=Fs=500N¡Á2m=1000J£¬
À­Á¦µÄ¹¦ÂÊ£º
P=$\frac{{W}_{×Ü}}{t}$=$\frac{1000J}{10s}$=100W£»
£¨4£©ÓÐÓù¦W_ÓÐÓÃ=Gh=800N¡Á1m=800J£¬
¸Ã»¬ÂÖ×éµÄ»úеЧÂÊ£º
¦Ç=$\frac{{W}_{ÓÐÓÃ}}{{W}_{×Ü}}$=$\frac{800J}{1000J}$¡Á100%=80%£»
£¨5£©Óøû¬ÂÖ×éÌáÉý1000NµÄÖØÎ¼´»¬ÂÖ×é²»±ä£¬ÔÚ¶îÍ⹦²»±äµÄÇé¿öÏ£¬ÎïÖØÔö¼Ó£¬ÔòÓÐÓù¦Ôö´ó£¬ÓɦÇ=$\frac{{W}_{ÓÐÓÃ}}{{W}_{×Ü}}$=$\frac{{W}_{ÓÐÓÃ}}{{W}_{ÓÐÓÃ}+{W}_{¶î}}$¿ÉÖª£¬´ËʱµÄ»úеЧÂʽ«±ä´ó£®
×ۺϷÖÎö¿ÉÖª£¬AD´í¡¢BCÕýÈ·£®
¹ÊÑ¡BC£®

µãÆÀ ±¾ÌâËäÈ»ÊÇÑ¡ÔñÌ⣬ʵÖÊÊÇÒ»×ۺϼÆËãÌ⣬¿¼²éÁËʹÓû¬ÂÖ×éÓÐÓù¦¡¢×ܹ¦¡¢¹¦ÂÊ¡¢»¬ÂÖ×éµÄ»úеЧÂÊÒÔ¼°¶¯»¬ÂÖÖصļÆË㣬ҪÇóѧÉúÊìÁ·ÕÆÎÕºÍÓ¦Óù«Ê½¼°Æä±äÐÎʽ£®