Question

9£®ÈçͼËùʾ£¬Ò»ÃûÏû·À¶ÓÔ±ÔÚ½øÐÐÄ£ÄâÑÝϰѵÁ·£¬Ëû´ÓÊúÖ±¹Ì¶¨ÔÚˮƽµØÃæÉϵĸ߶ÈL=16mµÄ¸Ö¹Ü¶¥¶ËÓɾ²Ö¹¿ªÊ¼ÍùÏ»¬£¬ËûÏÈÔȼÓËÙÏ»¬£¬ÔÙÔȼõËÙÏ»¬£¬»¬µ½µØÃæʱµÄËÙ¶ÈÇ¡ºÃΪÁ㣮ÒÑÖªÕâÃûÏû·À¶ÓÔ±µÄÖÊÁ¿m=50kg£¬Ëû¼ÓËÙʱµÄ¼ÓËٶȴóСÊǼõËÙʱµÄ¼ÓËٶȴóСµÄ3±¶£¬Ï»¬µÄ×Üʱ¼ät=4s£¬È¡ÖØÁ¦¼ÓËÙ¶Èg=10m/s²£¬¿ÉÖª¸ÃÏû·À¶ÓÔ±£¨¡¡¡¡£©

• A£® Ï»¬¹ý³ÌÖеÄ×î´óËÙ¶ÈΪ4¡¡m/s
• B£® ¼ÓËÙÓë¼õËÙ¹ý³ÌµÄʱ¼äÖ®±ÈΪ1£º3
• C£® ¼ÓËÙÓë¼õËÙ¹ý³ÌÖÐËùÊÜĦ²ÁÁ¦´óС֮±ÈΪ3£º19
• D£® ¼ÓËÙÓë¼õËÙ¹ý³ÌµÄλÒÆÖ®±ÈΪ1£º4

Answer 1

·ÖÎö ÓÉƽ¾ùËٶȹ«Ê½Çó½â×î´óËٶȣ®¸ù¾ÝËٶȹ«Ê½Ñо¿¼ÓËÙÓë¼õËÙ¹ý³ÌµÄʱ¼äÖ®±È£®¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂÉÑо¿Ä¦²ÁÁ¦Ö®±È£®

½â´ð ½â£ºA¡¢ÉèÏ»¬¹ý³ÌÖеÄ×î´óËÙ¶ÈΪv£¬ÔòÏû·À¶ÓԱϻ¬µÄ×ÜλÒÆΪ£º$x=\frac{v}{2}{t}_{1}+\frac{v}{2}{t}_{2}=\frac{v}{2}t$£¬µÃ£ºv=$\frac{2x}{t}=\frac{2¡Á16}{4}m/s=8m/s$£®¹ÊA´íÎó£®
B¡¢ÒòΪ¼ÓËÙʱµÄ¼ÓËٶȴóСÊǼõËÙʱµÄ3±¶£¬¸ù¾Ýv=atµÃ£¬¼ÓËÙÓë¼õËÙÔ˶¯µÄʱ¼äÖ®±ÈΪ1£º3£®¹ÊBÕýÈ·£®
C¡¢¿ÉÖª¼ÓËÙÔ˶¯µÄʱ¼äΪ1s£¬¼õËÙÔ˶¯µÄʱ¼äΪ3s£¬ÔòÓУº${a}_{1}=\frac{8}{1}=8m/{s}^{2}$£¬¼õËÙÔ˶¯µÄ¼ÓËٶȴóСΪ£º${a}_{2}=\frac{8}{3}m/{s}^{2}$£®
¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨Âɵ㬼ÓËÙ¹ý³Ì£ºmg-f₁=ma₁£¬f₁=mg-ma₁=2m
¼õËÙ¹ý³Ì£ºf₂-mg=ma₂£¬f₂=mg+ma₂=$\frac{38}{3}$m ËùÒÔf₁£ºf₂=3£º19£®¹ÊCÕýÈ·
D¡¢¼ÓËÙλÒÆ${x}_{1}=\frac{v}{2}{t}_{1}=4m$£¬¼õËÙλÒÆ${x}_{2}=\frac{v}{2}{t}_{2}=12m$£¬¹ÊλÒÆÖ®±ÈΪ1£º3£¬¹ÊD´íÎó£»
¹ÊÑ¡£ºBC

µãÆÀ ±¾ÌâÔËÓÃÅ£¶ÙµÚ¶þ¶¨ÂÉÔ˶¯Ñ§¹«Ê½½áºÏ·ÖÎö¶à¹ý³ÌÎÊÌ⣬Ҳ¿ÉÒÔ²ÉÓÃͼÏó·¨·ÖÎö×î´óËٶȣ®