Question

9£®ÈçͼËùʾ£¬ÓÐһˮƽ´«ËÍ´øÒÔ4m/sµÄËٶȰ´Ë³Ê±Õë·½ÏòÔÈËÙת¶¯£¬´«ËÍ´øÓÒ¶ËÁ¬×ÅÒ»¶Î¹â»¬Ë®Æ½ÃæBC£¬½ô°¤×ÅBCµÄ¹â»¬Ë®Æ½µØÃæDEÉÏ·ÅÖÃÒ»¸öÖÊÁ¿M=1kgµÄľ°å£¬Ä¾°åÉϱíÃæ¸ÕºÃÓëBCÃæµÈ¸ß£¬ÇÒľ°å×ã¹»³¤£®ÏÖ½«ÖÊÁ¿m=1kgµÄ»¬¿éÇáÇá·Åµ½´«ËÍ´øµÄ×ó¶ËA´¦£¬µ±»¬¿é»¬µ½´«ËÍ´øÓÒ¶ËBÖ®ºó»¬¿éÓÖͨ¹ý¹â»¬Ë®Æ½ÃæBC»¬ÉÏľ°å£®ÒÑÖªABÖ®¼äµÄ¾àÀëL=4m£¬»¬¿éÓë´«ËÍ´ø¼äµÄ¶¯Ä¦²ÁÒòÊý¦Ì₁=0.4£¬»¬¿éÓëľ°å¼äµÄ¶¯Ä¦²ÁÒòËئÌ₂=0.2£¬g=10m/s²£®Çó£º

£¨1£©»¬¿é´Ó´«ËÍ´øA¶Ë»¬µ½B¶ËËùÓõÄʱ¼ä£®
£¨2£©»¬¿é´Ó´«ËÍ´øA¶Ë»¬µ½B¶Ë£¬´«ËÍ´ø¶Ô»¬¿éËù×öµÄ¹¦£®
£¨3£©»¬¿éÔÚľ°åÉÏ»¬ÐеľàÀ룮

Answer 1

·ÖÎö £¨1£©»¬¿éÇáÇá·ÅÔÚ´«ËÍ´øÉϺó£¬ÓÉĦ²ÁÁ¦²úÉú¼ÓËٶȣ¬ÓÉÅ£¶ÙµÚ¶þ¶¨Âɼ´¿ÉÇó³ö¼ÓËٶȣ¬È»ºóÓÉÔ˶¯Ñ§µÄ¹«Ê½¼´¿ÉÇó³öʱ¼ä£»
£¨2£©¶Ô»¬¿é£¬ÔËÓö¯Äܶ¨ÀíÇó´«ËÍ´ø¶Ô»¬¿éËù×öµÄ¹¦£®
´«ËÍ´øÒò´«ËÍ»¬¿é¶àÏûºÄµÄµçÄÜת»¯Îª»¬¿éµÄ¶¯ÄܺÍÄÚÄÜ£»
£¨3£©»¬¿é»¬ÉÏľ°å£¬¶Ô»¬¿éºÍľ°åÊÜÁ¦·ÖÎö£¬Çó³ö¼ÓËٶȣ¬Ïà¶Ô¾²Ö¹Ê±ËÙ¶ÈÏàµÈ£¬ÓÉÔ˶¯Ñ§µÄ¹«Ê½¼´¿ÉÇó³öʱ¼äºÍ¹²Í¬Ëٶȣ¬ÔÙÇ󻬶¯ÔÚľ°åÉÏ»¬ÐеľàÀ룮

½â´ð ½â£º£¨1£©»¬¿éÇáÇá·ÅÔÚ´«ËÍ´øÉÏÊܵ½ÏòÓҵĻ¬¶¯Ä¦²ÁÁ¦£¬¼ÓËٶȴóСΪ£®
 a=$\frac{{¦Ì}_{1}mg}{m}$=¦Ì₁g=4m/s²
ËÙ¶ÈÔö´óÖÁÓë´«ËÍ´øÏàͬËùÓÃʱ¼ä t₁=$\frac{v}{a}$=$\frac{4}{4}$s=1s
ͨ¹ýµÄλÒÆ x₁=$\frac{1}{2}$at₁²=$\frac{1}{2}¡Á4¡Á{1}^{2}$m=2m£®
»¬¿éÔÈËÙÔ˶¯µÄʱ¼ä t₂=$\frac{L-{x}_{1}}{v}$=$\frac{4-2}{4}$s=0.5s
¹ÊËùÇóʱ¼äΪ t=t₁+t₂=1.5s
£¨2£©¸ù¾Ý¶¯Äܶ¨ÀíµÃ£º
´«ËÍ´ø¶Ô»¬¿éËù×öµÄ¹¦ W=$\frac{1}{2}m{v}^{2}$=$\frac{1}{2}¡Á1¡Á{4}^{2}$J=8J
£¨3£©»¬¿éÒÔ4m/sµÄËٶȻ¬ÉÏľ°å£¬¶Ô»¬¿éºÍľ°åÊÜÁ¦·ÖÎö£º
»¬¿éÊܵ½Ä¾°å¶ÔÆäÏò×óµÄĦ²ÁÁ¦£¬¼ÓËٶȴóСΪ
  a_»¬=$\frac{{¦Ì}_{2}mg}{m}$=g¦Ì₂=2m/s²    
ľ°åÊܵ½»¬¿é¶ÔÆäÏòÓÒµÄĦ²ÁÁ¦£¬¼ÓËٶȴóСΪ  a_ľ=$\frac{{¦Ì}_{2}mg}{M}$=2m/s²
É軬¿éÔÚľ°åÉϾ­¹ýʱ¼ät£¬Ä¾°åºÍ»¬¿é´ïµ½¹²Í¬ËÙ¶Èv_¹²
v_¹²=v-a_»¬t=a_ľt£¬µÃ t=$\frac{v}{{a}_{»¬}+{a}_{ľ}}$=$\frac{4}{4}$s=1s  
¶Ô»¬¿é£ºx_»¬=vt-$\frac{1}{2}$a_»¬t²£¬
¶Ôľ°å£ºx_ľ=$\frac{1}{2}$a_ľt²£¬
»¬¿éÔÚľ°åÉÏ»¬ÐеľàÀë d=x_»¬-x_ľ
´úÈëÊý¾ÝµÃ£ºd=2m
´ð£º
£¨1£©»¬¿é´Ó´«ËÍ´øA¶Ë»¬µ½B¶ËËùÓõÄʱ¼äÊÇ1.5s£®
£¨2£©»¬¿é´Ó´«ËÍ´øA¶Ë»¬µ½B¶Ë£¬´«ËÍ´ø¶Ô»¬¿éËù×öµÄ¹¦ÊÇ8J£®
£¨3£©»¬¿éÔÚľ°åÉÏ»¬ÐеľàÀëÊÇ2m£®

µãÆÀ ¸ÃÌ⿼²é´«ËÍ´øÄ£ÐÍÓ뻬¿é-ľ°åÄ£ÐÍ£¬½â¾ö±¾ÌâµÄ¹Ø¼üÀíÇåÎï¿éÔÚ´«ËÍ´øÉϺÍľ°åÉϵÄÔ˶¯¹æÂÉ£¬½áºÏÔ˶¯Ñ§¹«Ê½ºÍÅ£¶ÙµÚ¶þ¶¨ÂɽøÐÐÇó½â£®»¬¿é-ľ°åÒ²¿ÉÒÔʹÓö¯Á¿Êغ㶨ÂɺÍÄÜÁ¿Êغ㶨ÂɽáºÏÀ´½â´ð£®