ÌâÄ¿ÄÚÈÝ
ÈçͼËùʾ£¬Ë®Æ½×ÀÃæ¾àµØÃæµÄ¸ß¶Èh=0.80m£®¿ÉÒÔ¿´³ÉÖʵãµÄС½ðÊô¿éCµÄÖÊÁ¿m1=0.50kg£¬·ÅÔÚºñ¶È²»¼ÆµÄ³¤Ä¾°åABÉÏ£®Ä¾°å³¤L=0.865m£¬ÖÊÁ¿m2=0.20kg£¬Ä¾°åµÄA¶Ë¸ú×ÀÃæµÄ±ßÔµ¶ÔÆ룮С½ðÊô¿éCµ½Ä¾°åB¶ËµÄ¾àÀëd=0.375m£®¼Ù¶¨Ð¡½ðÊô¿éÓëľ°å¼ä¡¢Ä¾°åÓë×ÀÃæ¼ä¡¢Ð¡½ðÊô¿éÓë×ÀÃæ¼äµÄ¶¯Ä¦²ÁÒòÊý¶¼ÏàµÈ£¬ÆäÖµ¦Ì=0.20£®ÏÖÓÃÁ¦½«Ä¾°åˮƽÏòÓÒ¼ÓËÙ³é³ö£¬ÔÚС½ðÊô¿é´Óľ°åÉÏ»¬ÏÂÒÔÇ°£¬¼ÓÔÚľ°åÉϵÄÁ¦ÎªË®Æ½ÏòÓҵĺãÁ¦F£®Ð¡½ðÊô¿éÂäµ½×ÀÃæÉϺó£¬ÓÖÔÚ×ÀÃæÉÏ»¬¶¯ÁËÒ»¶Î¾àÀ룬ÔÙ´Ó×ÀÃæ±ßÔµ·É³öÂ䵽ˮƽµØÃæÉÏ£¬Ð¡½ðÊô¿éÂäµØµãµ½×À±ßµÄˮƽ¾àÀës=0.08m£®Çó£º
£¨1£©×÷ÓÃÔÚľ°åÉϵĺãÁ¦FµÄ´óС£®
£¨2£©ÈôÏ£ÍûС½ðÊô¿é²»»¬³ö×ÀÃ棬ÔòºãÁ¦µÄ´óСӦ¸ÃÈçºÎµ÷Õû£¬Çë˵Ã÷ÀíÓÉ£®
£¨1£©×÷ÓÃÔÚľ°åÉϵĺãÁ¦FµÄ´óС£®
£¨2£©ÈôÏ£ÍûС½ðÊô¿é²»»¬³ö×ÀÃ棬ÔòºãÁ¦µÄ´óСӦ¸ÃÈçºÎµ÷Õû£¬Çë˵Ã÷ÀíÓÉ£®
·ÖÎö£º£¨1£©½ðÊô¿é¾ÀúÁËÔÚľ°åÉϵÄÔȼÓËÙÖ±ÏßÔ˶¯£¬´Óľ°åÉÏ»¬ÂäºóÔÚ×ÀÃæÉϵÄÔȼõËÙÖ±ÏßÔ˶¯£¬À뿪×ÀÃæºóµÄƽÅ×Ô˶¯£®×¥×¡Æ½Å×Ô˶¯µÄ³õËٶȣ¬¼´ÔÚˮƽÃæÉÏÔ˶¯µÄÄ©Ëٶȣ¬½áºÏÅ£¶ÙµÚ¶þ¶¨ÂɺÍÔ˶¯Ñ§¹«Ê½Çó³öľ°åµÄ¼ÓËٶȣ¬´Ó¶øÇó³öÀÁ¦µÄ´óС£®
£¨2£©½ðÊô¿é²»»¬Àë×ÀÃæµÄÁÙ½çËÙ¶ÈÊǵ½´ï×ÀÃæµÄÄ©ËÙ¶ÈËÙ¶ÈΪÁ㣬½áºÏÅ£¶ÙµÚ¶þ¶¨ÂɺÍÔ˶¯Ñ§¹«Ê½£¬×¥×¡½ðÊô¿éµÄλÒÆÖ®ºÍµÈÓÚL-d£¬Ä¾°åÓë½ðÊô¿éµÄλÒÆÖ®²îµÈÓÚd£¬Çó³öÁ¦FµÄ·¶Î§£®
£¨2£©½ðÊô¿é²»»¬Àë×ÀÃæµÄÁÙ½çËÙ¶ÈÊǵ½´ï×ÀÃæµÄÄ©ËÙ¶ÈËÙ¶ÈΪÁ㣬½áºÏÅ£¶ÙµÚ¶þ¶¨ÂɺÍÔ˶¯Ñ§¹«Ê½£¬×¥×¡½ðÊô¿éµÄλÒÆÖ®ºÍµÈÓÚL-d£¬Ä¾°åÓë½ðÊô¿éµÄλÒÆÖ®²îµÈÓÚd£¬Çó³öÁ¦FµÄ·¶Î§£®
½â´ð£º½â£º£¨1£©Ð¡½ðÊô¿é¾ÀúÁËÈý¶ÎÔ˶¯¹ý³Ì£ºÔÚľ°åÉϵÄÔȼÓËÙÖ±ÏßÔ˶¯£¬´Óľ°åÉÏ»¬ÂäºóÔÚ×ÀÃæÉϵÄÔȼõËÙÖ±ÏßÔ˶¯£¬À뿪×ÀÃæºóµÄƽÅ×Ô˶¯£®
ÉèС½ðÊô¿é×öƽÅ×Ô˶¯µÄʱ¼äΪt3£¬h=
g
t3=
=
=0.4(s)
ÉèƽÅ×Ô˶¯µÄ³õËÙ¶ÈΪv2£¬s=v2t3
v2=
=
=0.2(m/s)
С½ðÊô¿éÔÚ³¤Ä¾°åÉÏÔ˶¯Ê±µÄÊÜÁ¦Èçͼ1Ëùʾ£¬Ð¡½ðÊô¿éÕâʱ×öÔȼÓËÙÖ±ÏßÔ˶¯£¬ÉèËüµÄ¼ÓËÙ¶ÈΪa1£®
f1=¦ÌF1=¦Ìm1g=0.20¡Á0.50¡Á10=1.0£¨N£©
a1=
=
=2.0(m/s2)
С½ðÊô¿éÀ뿪³¤Ä¾°åºóÔÚ×ÀÃæÉÏÔ˶¯Ê±µÄÊÜÁ¦Èçͼ2Ëùʾ£¬Ð¡½ðÊô¿éÕâʱ×öÔȼõËÙÖ±ÏßÔ˶¯£¬ÉèËüµÄ¼ÓËٶȵĴóСΪa'1£®
f'1=¦ÌF1=¦Ìm1g=0.2¡Á0.5¡Á10=1.0£¨N£©
a¡ä1=
=
=2.0(m/s2)
a'1=a1
ÉèС½ðÊô¿éÔÚľ°åÉÏÔ˶¯Ê±£¬Ïà¶ÔÓÚµØÃæÔ˶¯µÄ¾àÀëΪs1£¬Ä©ËÙ¶ÈΪv1£¬ËùÓÃʱ¼äΪt1£¬s1=
¢Ù
v1=a1t1¢Ú
ÉèС½ðÊô¿éÔÚ×ÀÃæÉÏÔ˶¯Ê±£¬Ïà¶ÔÓÚµØÃæÔ˶¯µÄ¾àÀëΪs2£¬Ä©ËÙ¶ÈΪv2£¬-2a1s2=
-
¢Û
ÓÉÌâÒâÖªs1+s2=L-d¢Ü
ÁªÁ¢ÒÔÉÏËÄʽ£¬½âµÃs1=0.25m¡¢s2=0.24m¡¢t1=0.5s¡¢v1=1.0m/s
ȡľ°åΪÑо¿¶ÔÏó£¬Ð¡½ðÊô¿éÔÚľ°åÉÏÔ˶¯Ê±£¬Ä¾°åÊÜÁ¦Èçͼ3Ëùʾ£®f2=¦ÌF2=¦Ì£¨m1+m2£©g=0.20¡Á0.70¡Á10=1.4£¨N£©
ľ°åÔÚt1ʱ¼äÄÚÏòÓÒÔ˶¯¾àÀëΪd+s1£¬Éèľ°åµÄ¼ÓËÙ¶ÈΪa2£¬Ôòd+s1=
a2
a2=
=
=5.0(m/s2)
ÀûÓÃÅ£¶Ù¶¨ÂÉF-£¨f1+f2£©=m2a2¡¢
½âµÃF=3.4N£®
£¨2£©Èô½ðÊô¿é²»»¬³ö×ÀÃ棬ÁÙ½çÇé¿öÊÇ»¬¿éµ½´ï×ÀÃæµÄÓÒ¶ËËٶȱäΪÁ㣮
ÉèÎï¿éÀ뿪ľ°åʱµÄËÙ¶ÈΪv£¬ÓУº
+
=L-d£®
½âµÃv=0.7
m/s£®
ÔòÔÚľ°åÉÏÔ˶¯µÄʱ¼ät=
=
s£®
a2t2-
a1t2=d
½âµÃľ°åµÄ¼ÓËÙ¶Èa2¡Ö5.1m/s2
¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨Âɵã¬F¡ä-£¨f1+f2£©=m2a2
½âµÃF¡ä=3.42N£®
¼´F¡Ý3.42N£¬Ð¡½ðÊô¿é²»»¬³ö×ÀÃ森
´ð£º£¨1£©×÷ÓÃÔÚľ°åÉϵĺãÁ¦FµÄ´óСΪ3.4N£®
£¨2£©F¡Ý3.42N£¬Ð¡½ðÊô¿é²»»¬³ö×ÀÃ森
ÉèС½ðÊô¿é×öƽÅ×Ô˶¯µÄʱ¼äΪt3£¬h=
1 |
2 |
t | 2 3 |
t3=
|
|
ÉèƽÅ×Ô˶¯µÄ³õËÙ¶ÈΪv2£¬s=v2t3
v2=
s |
t3 |
0.08 |
0.4 |
С½ðÊô¿éÔÚ³¤Ä¾°åÉÏÔ˶¯Ê±µÄÊÜÁ¦Èçͼ1Ëùʾ£¬Ð¡½ðÊô¿éÕâʱ×öÔȼÓËÙÖ±ÏßÔ˶¯£¬ÉèËüµÄ¼ÓËÙ¶ÈΪa1£®
f1=¦ÌF1=¦Ìm1g=0.20¡Á0.50¡Á10=1.0£¨N£©
a1=
f1 |
m1 |
1.0 |
0.5 |
С½ðÊô¿éÀ뿪³¤Ä¾°åºóÔÚ×ÀÃæÉÏÔ˶¯Ê±µÄÊÜÁ¦Èçͼ2Ëùʾ£¬Ð¡½ðÊô¿éÕâʱ×öÔȼõËÙÖ±ÏßÔ˶¯£¬ÉèËüµÄ¼ÓËٶȵĴóСΪa'1£®
f'1=¦ÌF1=¦Ìm1g=0.2¡Á0.5¡Á10=1.0£¨N£©
a¡ä1=
f¡ä1 |
m1 |
1.0 |
0.5 |
a'1=a1
ÉèС½ðÊô¿éÔÚľ°åÉÏÔ˶¯Ê±£¬Ïà¶ÔÓÚµØÃæÔ˶¯µÄ¾àÀëΪs1£¬Ä©ËÙ¶ÈΪv1£¬ËùÓÃʱ¼äΪt1£¬s1=
| ||
2a1 |
v1=a1t1¢Ú
ÉèС½ðÊô¿éÔÚ×ÀÃæÉÏÔ˶¯Ê±£¬Ïà¶ÔÓÚµØÃæÔ˶¯µÄ¾àÀëΪs2£¬Ä©ËÙ¶ÈΪv2£¬-2a1s2=
v | 2 2 |
v | 2 1 |
ÓÉÌâÒâÖªs1+s2=L-d¢Ü
ÁªÁ¢ÒÔÉÏËÄʽ£¬½âµÃs1=0.25m¡¢s2=0.24m¡¢t1=0.5s¡¢v1=1.0m/s
ȡľ°åΪÑо¿¶ÔÏó£¬Ð¡½ðÊô¿éÔÚľ°åÉÏÔ˶¯Ê±£¬Ä¾°åÊÜÁ¦Èçͼ3Ëùʾ£®f2=¦ÌF2=¦Ì£¨m1+m2£©g=0.20¡Á0.70¡Á10=1.4£¨N£©
ľ°åÔÚt1ʱ¼äÄÚÏòÓÒÔ˶¯¾àÀëΪd+s1£¬Éèľ°åµÄ¼ÓËÙ¶ÈΪa2£¬Ôòd+s1=
1 |
2 |
t | 2 1 |
a2=
2(d+s1) | ||
|
2(0.375+0.25) |
0.52 |
ÀûÓÃÅ£¶Ù¶¨ÂÉF-£¨f1+f2£©=m2a2¡¢
½âµÃF=3.4N£®
£¨2£©Èô½ðÊô¿é²»»¬³ö×ÀÃ棬ÁÙ½çÇé¿öÊÇ»¬¿éµ½´ï×ÀÃæµÄÓÒ¶ËËٶȱäΪÁ㣮
ÉèÎï¿éÀ뿪ľ°åʱµÄËÙ¶ÈΪv£¬ÓУº
v2 |
2a1 |
v2 |
2a1¡ä |
½âµÃv=0.7
2 |
ÔòÔÚľ°åÉÏÔ˶¯µÄʱ¼ät=
v |
a |
0.7
| ||
2 |
1 |
2 |
1 |
2 |
½âµÃľ°åµÄ¼ÓËÙ¶Èa2¡Ö5.1m/s2
¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨Âɵã¬F¡ä-£¨f1+f2£©=m2a2
½âµÃF¡ä=3.42N£®
¼´F¡Ý3.42N£¬Ð¡½ðÊô¿é²»»¬³ö×ÀÃ森
´ð£º£¨1£©×÷ÓÃÔÚľ°åÉϵĺãÁ¦FµÄ´óСΪ3.4N£®
£¨2£©F¡Ý3.42N£¬Ð¡½ðÊô¿é²»»¬³ö×ÀÃ森
µãÆÀ£º½â¾ö±¾ÌâµÄ¹Ø¼üÀíÇå½ðÊô¿éµÄÔ˶¯Çé¿ö£¬ÒÔ¼°×¥×¡¹ý³ÌÖеÄÁÙ½çÇé¿ö£¬½áºÏÅ£¶ÙµÚ¶þ¶¨ÂɺÍÔ˶¯Ñ§¹«Ê½½øÐÐÇó½â£®
Á·Ï°²áϵÁдð°¸
Ïà¹ØÌâÄ¿