ÌâÄ¿ÄÚÈÝ
ÈçͼËùʾ£¬ÔÚÖÊÁ¿ÎªmB=30kgµÄ³µÏáBÄÚ½ô¿¿ÓÒ±Ú£¬·ÅÒ»ÖÊÁ¿mA=20kgµÄСÎïÌåA£¨¿ÉÊÓΪÖʵ㣩£¬¶Ô³µÏáBÊ©¼ÓһˮƽÏòÓҵĺãÁ¦F£¬ÇÒF=120N£¬Ê¹Ö®´Ó¾²Ö¹¿ªÊ¼Ô˶¯£®²âµÃ³µÏáBÔÚ×î³õt=2.0sÄÚÒƶ¯s=5.0m£¬ÇÒÕâ¶Îʱ¼äÄÚСÎï¿éδÓë³µÏá±Ú·¢Éú¹ýÅöײ£®³µÏáÓëµØÃæ¼äµÄĦ²ÁºöÂÔ²»¼Æ£¨¡¡¡¡£©
![¾«Ó¢¼Ò½ÌÍø](http://thumb.1010pic.com/pic2/upload/papers/20131203/201312031217517741932.png)
A£®³µÏáBÔÚ2.0sÄڵļÓËÙ¶ÈΪ2.5m/s2 |
B£®AÔÚ2.0sÄ©µÄËٶȴóСÊÇ4.5m/s |
C£®2.0sÄÚAÔÚBÉÏ»¬¶¯µÄ¾àÀëÊÇ0.5m |
D£®AµÄ¼ÓËٶȴóСΪ2.5m/s2 |
![¾«Ó¢¼Ò½ÌÍø](http://thumb.1010pic.com/pic2/upload/papers/20131203/201312031217517741932.png)
A¡¢Éèt=2.0sÄÚ³µÏáµÄ¼ÓËÙ¶ÈΪaB£¬ÓÉs=
aBt2µÃaB=2.5m/s2£®¹ÊAÕýÈ·£®
B¡¢D£º¶ÔB£¬ÓÉÅ£¶ÙµÚ¶þ¶¨ÂÉ£ºF-f=mBaB£¬µÃf=45N£®
¶ÔA£¬¾ÝÅ£¶ÙµÚ¶þ¶¨ÂɵÃAµÄ¼ÓËٶȴóСΪaA=
=2.25m/s2
ËùÒÔt=2.0sÄ©AµÄËٶȴóСΪ£ºvA=aAt=4.5m/s£®
¹ÊBÕýÈ·¡¢D´íÎó£®
C¡¢ÔÚt=2.0sÄÚAÔ˶¯µÄλÒÆΪsA=
aAt2=4.5m£¬
AÔÚBÉÏ»¬¶¯µÄ¾àÀë¡÷s=s-sA=0.5m£®¹ÊCÕýÈ·£®
¹ÊÑ¡ABC£®
1 |
2 |
B¡¢D£º¶ÔB£¬ÓÉÅ£¶ÙµÚ¶þ¶¨ÂÉ£ºF-f=mBaB£¬µÃf=45N£®
¶ÔA£¬¾ÝÅ£¶ÙµÚ¶þ¶¨ÂɵÃAµÄ¼ÓËٶȴóСΪaA=
f |
mA |
ËùÒÔt=2.0sÄ©AµÄËٶȴóСΪ£ºvA=aAt=4.5m/s£®
¹ÊBÕýÈ·¡¢D´íÎó£®
C¡¢ÔÚt=2.0sÄÚAÔ˶¯µÄλÒÆΪsA=
1 |
2 |
AÔÚBÉÏ»¬¶¯µÄ¾àÀë¡÷s=s-sA=0.5m£®¹ÊCÕýÈ·£®
¹ÊÑ¡ABC£®
![](http://thumb2018.1010pic.com/images/loading.gif)
Á·Ï°²áϵÁдð°¸
Ïà¹ØÌâÄ¿