Question

7£®ÈçͼËùʾ£¬³¤ÎªL=6m¡¢ÖÊÁ¿M=4kgµÄ³¤Ä¾°å·ÅÖÃÓڹ⻬µÄˮƽÃæÉÏ£¬Æä×ó¶ËÓÐÒ»´óС¿ÉºöÂÔ£¬ÖÊÁ¿Îªm=1kgµÄÎï¿é£¬Îï¿éÓëľ°å¼äµÄ¶¯Ä¦²ÁÒòÊýΪ0.2£¬¿ªÊ¼Ê±Îï¿éÓëľ°å¶¼´¦ÓÚ¾²Ö¹×´Ì¬£¬ÏÖ¶ÔÎï¿éMÊ©¼ÓF=6N£¬·½ÏòˮƽÏòÓҵĺ㶨À­Á¦£¬Ç󣺣¨g=10m/s²£©
£¨1£©Ð¡Îï¿éµÄ¼ÓËٶȣ»
£¨2£©Èô´ËºãÁ¦×÷ÓÃÔÚСÎï¿éÉÏ£¬ÇóÎï¿éMµÄ¼ÓËٶȣ®
£¨3£©ÔÚµÚ£¨2£©ÎʵĻù´¡ÉÏÈôСÎï¿éÄÜ´Óľ°å×ó¶ËÔ˶¯µ½ÓÒ¶ËÇó¾­ÀúµÄʱ¼ä£®

Answer 1

·ÖÎö £¨1£©ÕûÌå·ÖÎöÇóµÃÁ¦F×÷ÓÃMÉÏÕûÌåµÄ¼ÓËٶȣ¬ÔÙ·ÖÎöm£¬ÓÉÅ£¶ÙÔ˶¯¶¨ÂÉÇóµÃmµÄ¼ÓËٶȣ»
£¨2£©¶Ôm·ÖÎöÇóµÃmµÄ¼ÓËٶȣ¬ÔÙ¶Ô³¤Ä¾°åMÊÜÁ¦·ÖÎöÇóµÃMµÄ¼ÓËٶȼ´¿É£®
£¨3£©Ð¡Îï¿éÏòÓÒ¼ÓËÙÔ˶¯£¬³¤Ä¾°åÒàÏòÓÒ¼ÓËÙÔ˶¯£¬Á½ÕßλÒƲîΪľ°å³¤¶ÈʱСÎï¿éµ½´ïľ°åµÄÓҶˣ¬¸ù¾ÝλÒÆʱ¼ä¹ØϵÇó½â¼´¿É£®

½â´ð ½â£º£¨1£©ÒÔmºÍMÕûÌåΪÑо¿¶ÔÏó½øÐÐÊÜÁ¦·ÖÎö¿ÉµÃ£º
F=£¨M+m£©a
¿ÉµÃÕûÌåÔ˶¯µÄ¼ÓËÙ¶ÈΪ£ºa=$\frac{F}{M+m}=\frac{6}{4+1}m/{s}^{2}=1.2m/{s}^{2}$
ÔÙÒÔmΪÑо¿¶ÔÏ󣬻¬¶¯Ä¦²ÁÁ¦Ê¹m²úÉúµÄ×î´ó¼ÓËÙ¶ÈΪ£º
${a}_{m}=\frac{f}{m}=\frac{¦Ìmg}{m}=¦Ìg=0.2¡Á10m/{s}^{2}=2m/{s}^{2}$
ÒòΪa£¼a_m
ËùÒÔСÎï¿éµÄ¼ÓËÙ¶ÈΪ£ºa=1.2m/s²£»
£¨2£©ºãÁ¦×÷ÓÃÔÚСÎï¿éÉÏ£¬¶ÔСÎï¿é½øÐÐÊÜÁ¦·ÖÎö¿ÉµÃ£º
F-f=ma¡ä
f=¦Ìmg
ËùÒԿɵÃСÎï¿éµÄ¼ÓËÙ¶ÈΪ£ºa¡ä=$\frac{F-¦Ìmg}{m}=\frac{6-0.2¡Á1¡Á10}{1}m/{s}^{2}=4m/{s}^{2}$
´ËʱÒÔ³¤Ä¾°åΪÑо¿¶ÔÏ󣬿ÉÖª£º
f=Ma¡å
¿ÉµÃ³¤Ä¾°åµÄ¼ÓËÙ¶ÈΪ£º$a¡å\frac{f}{M}=\frac{0.2¡Á1¡Á10}{4}m/{s}^{2}0.5m/{s}^{2}$
£¨3£©ÒªÊ¹Ð¡Ä¾¿é´Óľ°å×ó¶ËÔ˶¯µ½ÓҶˣ¬Î»ÒƹØϵÂú×㣺
s_m-s_M=L
ÓÉλÒƹØϵµÃ£º
$\frac{1}{2}a¡ä{t}^{2}-\frac{1}{2}a¡å{t}^{2}=L$
¼´$\frac{1}{2}¡Á4¡Á{t}^{2}-\frac{1}{2}¡Á0.5¡Á{t}^{2}=6m$
¿É½âµÃ£ºt=1.85s
´ð£º£¨1£©Ð¡Îï¿éµÄ¼ÓËÙ¶ÈΪ1.2m/s²£»
£¨2£©Èô´ËºãÁ¦×÷ÓÃÔÚСÎï¿éÉÏ£¬Îï¿éMµÄ¼ÓËÙ¶ÈΪ0.5 m/s²£»
£¨3£©ÔÚµÚ£¨2£©ÎʵĻù´¡ÉÏÈôСÎï¿éÄÜ´Óľ°å×ó¶ËÔ˶¯µ½ÓҶ˾­ÀúµÄʱ¼äΪ1.85s£®

µãÆÀ ±¾Ì⿼²éÁËÅ£¶ÙµÚ¶þ¶¨ÂɺÍÔ˶¯Ñ§¹«Ê½µÄ»ù±¾ÔËÓã¬ÖªµÀ¼ÓËÙ¶ÈÊÇÁªÏµÁ¦Ñ§ºÍÔ˶¯Ñ§µÄÇÅÁº£®