Question

4£®ÓÐÒ»Á¾Æû³µÔÈËÙÐÐÊ»Ôڸ߶ÈΪ20m£¬Çãб½Ç¶ÈΪ30¡ãµÄбÆ£¬´ËʱÆû³µÒýÇæÇ£ÒýÁ¦Îª500N£¬ÓÃʱ5s£®ÈôбÃæµÄ»úеЧÂÊÊÇ40%£®ÊÔÇó£º
£¨1£©Ç£ÒýÁ¦Ëù×öµÄ¹¦ÊǶàÉÙ£¿
£¨2£©Æû³µËùÊܵÄĦ²ÁÁ¦ÊǶàÉÙ£¿
£¨3£©ÔÚÆû³µÅÀƹý³ÌÖУ¬Ë¾»ú½«ÓÍÃżӵ½×î´óÈÔ»á³öÏÖ¶¯Á¦²»×ãµÄÇé¿ö£¬ÇëΪ˾»úÌṩһ¸ö½â¾ö·½·¨²¢ËµÃ÷£»
£¨4£©Ò»¶Îʱ¼äºó£¬Æû³µµ½´ïбƶ¥£®µ±Ë¾»úÀ뿪ʱÍüÁË¿ªÆôÊÖɲ£¬Æû³µÂýÂý¼ÓËÙÏòбƵ׵¹³µ£®´ËʱÆû³µËùÊܵ½µÄĦ²ÁÁ¦µÈÓÚ£¨Ñ¡Ìî¡°´óÓÚ¡±¡¢¡°Ð¡ÓÚ¡±»ò¡°µÈÓÚ¡±£©Æû³µÉÏÆÂʱËùÊÜĦ²ÁÁ¦£®

Answer 1

·ÖÎö £¨1£©ÓÉÌâ֪бƸߺÍÇãб½Ç¶È£¬ÀûÓÃÖ±½ÇÈý½ÇÐεı߽ǹØϵÇóбƳ¤£»ÀûÓÃW=FsÇóÇ£ÒýÁ¦Ëù×öµÄ¹¦£»
£¨2£©ÓɦÇ=$\frac{{W}_{ÓÐÓÃ}}{{W}_{×Ü}}$µÃÓÐÓù¦£¬¶ø¶îÍ⹦W_¶î=W_×Ü-W_ÓÐÓã¬ÔÙÀûÓÃW=FsÇóĦ²ÁÁ¦£»
£¨3£©Æû³µÅÀƹý³ÌÖУ¬Æû³µµÄÊä³ö¹¦ÂÊÒ»¶¨£¬ÀûÓÃP=Fv·ÖÎö»Ø´ð£»
£¨4£©»¬¶¯Ä¦²ÁÁ¦ÓëѹÁ¦ºÍ½Ó´¥ÃæµÄ´Ö²Ú³Ì¶ÈÓйأ®

½â´ð ½â£º£¨1£©ÓÉÌâÖª£¬Ð±Ãæ¸ßh=20m£¬Çãб½Ç¶ÈΪ30¡ã£¬
¸ù¾ÝÊýѧ֪ʶÓУº$\frac{h}{s}$=sin30¡ã=$\frac{1}{2}$£¬
ËùÒÔбÃæµÄ³¤¶È£ºs=2h=2¡Á20m=40m£»
Ç£ÒýÁ¦Ëù×öµÄ¹¦£ºW_×Ü=Fs=500N¡Á40m=20000J£»
£¨2£©ÓɦÇ=$\frac{{W}_{ÓÐÓÃ}}{{W}_{×Ü}}$µÃÓÐÓù¦£º
W_ÓÐÓÃ=W_×Ü¡Á¦Ç=W_×Ü¡Á40%=20000J¡Á40%=8000J£¬
¶îÍ⹦£ºW_¶î=W_×Ü-W_ÓÐÓÃ=20000J-8000J=12000J£¬
¸ù¾ÝW=Fs¿ÉµÃĦ²ÁÁ¦£º
f=$\frac{{W}_{¶î}}{s}$=$\frac{12000J}{40m}$=300N£»
£¨3£©Æû³µÅÀƹý³ÌÖУ¬Ë¾»ú¿É½µµÍ³µËÙ£¬Æû³µµÄÊä³ö¹¦ÂÊÒ»¶¨£¬ÓÉP=Fv¿ÉÖª£¬FÓëv³É·´±È£¬Æû³µ¿ÉÒÔ»ñµÃ¸ü´óµÄÇ£ÒýÁ¦£»
£¨4£©Æû³µÏòбƵ׵¹³µºÍÅÀÆÂÏà±È£¬Æû³µ¶ÔбƵÄѹÁ¦¡¢½Ó´¥ÃæµÄ´Ö²Ú³Ì¶È¶¼²»±ä£¬Æû³µÊܵ½µÄĦ²ÁÁ¦²»±ä£¬ËùÒÔ´ËʱÆû³µËùÊܵ½µÄĦ²ÁÁ¦µÈÓÚÆû³µÉÏÆÂʱËùÊÜĦ²ÁÁ¦£®
´ð£º£¨1£©Ç£ÒýÁ¦Ëù×öµÄ¹¦ÊÇ20000J£»
£¨2£©Æû³µËùÊܵÄĦ²ÁÁ¦ÊÇ300N£»
£¨3£©Æû³µµÄÊä³ö¹¦ÂÊÒ»¶¨£¬ÓÉP=Fv¿ÉÖª£¬½µµÍ³µËÙ£¬Æû³µ¿ÉÒÔ»ñµÃ¸ü´óµÄÇ£ÒýÁ¦£»
£¨4£©µÈÓÚ£®

µãÆÀ ±¾Ì⿼²éÁËʹÓÃбÃæÓÐÓù¦¡¢×ܹ¦¡¢¶îÍ⹦¡¢Ä¦²ÁÁ¦µÄ¼ÆË㣬¼ÆËãʱעÒâĦ²ÁÁ¦²»µÈÓÚÆû³µÖØÁ¦£¬Ò×´íµã£¡