题目内容
质量60kg的人通过光滑的定滑轮拉动质量20kg的物体,如图所示,当物体以5m/s2的加速度加速上升时,人对地面的压力等于(g=10m/s2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241326314981573.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241326314981573.jpg)
A.300N | B.800N? |
C.600N | D.400 N |
A
对物体受力分析有:
,
,对人受力分析有:
,N=300N,A正确。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132631514612.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132631545592.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132631623701.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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题目内容
A.300N | B.800N? |
C.600N | D.400 N |