Question

12£®ÈçͼËùʾ£¬ÖÊÁ¿Îªm=20kgµÄÖ½ÏäÔÚÀ­Á¦FµÄ×÷ÓÃÏÂÑØˮƽµØÃæÔ˶¯£¬À­Á¦F=100N£¬·½ÏòÓëˮƽÃæµÄ¼Ð½ÇΪ¦È=53¡ã£¬Ö½ÏäÓëˮƽµØÃæµÄ¶¯Ä¦²ÁÒòÊý¦Ì=0.2£®£¨È¡g=10m/s²£¬sin53¡ã=0.8£¬cos53¡ã=0.6£©
£¨1£©ÇóÖ½ÏäÊܵ½µÄÖ§³ÖÁ¦ºÍĦ²ÁÁ¦µÄ´óС£®
£¨2£©Ö½ÏäÓɾ²Ö¹¿ªÊ¼Ô˶¯£¬2sÄÚµÄλÒƶà´ó£¿
£¨3£©Èô2sºó³·È¥À­Á¦£¬Ïä×Ó»¹ÄÜ»¬ÐжàԶͣÏÂÀ´£¿

Answer 1

·ÖÎö £¨1£©¸ù¾ÝÊúÖ±·½ÏòÉÏƽºâÇó³öÖ§³ÖÁ¦µÄ´óС£¬½áºÏ»¬¶¯Ä¦²ÁÁ¦¹«Ê½Çó³öĦ²ÁÁ¦µÄ´óС£®
£¨2£©¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂÉÇó³öÖ½ÏäµÄ¼ÓËٶȣ¬½áºÏλÒÆʱ¼ä¹«Ê½Çó³ö2sÄÚµÄλÒÆ£®
£¨3£©¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂÉÇó³ö³·È¥À­Á¦ºóµÄ¼ÓËٶȴóС£¬¸ù¾ÝËÙ¶Èʱ¼ä¹«Ê½Çó³ö2sÄ©µÄËٶȣ¬½áºÏËÙ¶ÈλÒƹ«Ê½Çó³ö»¹ÄÜ»¬ÐеľàÀ룮

½â´ð ½â£º£¨1£©¸ù¾ÝÊúÖ±·½ÏòÉÏƽºâÓУºN+Fsin53¡ã=mg£¬
½âµÃÖ§³ÖÁ¦N=mg-Fsin53¡ã=200-100¡Á0.8N=120N£®
ÔòĦ²ÁÁ¦µÄ´óСf=¦ÌN=0.2¡Á120N=24N£®
£¨2£©¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨Âɵ㬼ÓËÙ¶Èa=$\frac{Fcos53¡ã-f}{m}=\frac{100¡Á0.6-24}{20}$=1.8m/s²£¬
2sÄÚµÄλÒÆx=$\frac{1}{2}a{t}^{2}=\frac{1}{2}¡Á1.8¡Á4m=3.6m$£®
£¨2£©³·È¥À­Á¦ºóµÄ¼ÓËٶȴóС$a¡ä=\frac{¦Ìmg}{m}=¦Ìg=0.2¡Á10m/{s}^{2}=2m/{s}^{2}$£¬
2sÄ©µÄËÙ¶Èv=at=1.8¡Á2m/s=3.6m/s£¬
Ïä×Ó»¹ÄÜ»¬ÐеľàÀëx¡ä=$\frac{{v}^{2}}{2a¡ä}=\frac{3£®{6}^{2}}{4}m=3.24m$£®
´ð£º£¨1£©Ö½ÏäÊܵ½µÄÖ§³ÖÁ¦Îª120N£¬Ä¦²ÁÁ¦µÄ´óСΪ24N£®
£¨2£©Ö½ÏäÓɾ²Ö¹¿ªÊ¼Ô˶¯£¬2sÄÚµÄλÒÆΪ3.6m£®
£¨3£©Èô2sºó³·È¥À­Á¦£¬Ïä×Ó»¹ÄÜ»¬ÐÐ3.24mÍ£ÏÂÀ´£®

µãÆÀ ±¾Ì⿼²éÁËÅ£¶ÙµÚ¶þ¶¨ÂɺÍÔ˶¯Ñ§¹«Ê½µÄ×ÛºÏÔËÓã¬ÖªµÀ¼ÓËÙ¶ÈÊÇÁªÏµÁ¦Ñ§ºÍÔ˶¯Ñ§µÄÇÅÁº£¬×¢Òâ³·È¥FÇ°ºóµÄĦ²ÁÁ¦´óС²»Í¬£®