题目内容
质量为m="10" kg的物体,静止在斜面上,斜面的倾角为30°,在10 s内,下列说法正确的是( )
A.重力对物体的冲量为500 N·s节 | B.支持力对物体的冲量为零 |
C.摩擦力对物体的冲量无法计算 | D.合外力对物体的冲量为零 |
D
物体受力如图所示,Ff=mgsin30°="50" N
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241208215992649.jpg)
FN=mgcos30°=100×
N
IG="mgt=1" 000 N·s
IN=50
×10 N·s=500
N·s
If=50×10 N·s="500" N·s
F合=0,由I=Ft,可知选D.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241208215992649.jpg)
FN=mgcos30°=100×
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120821599571.gif)
IG="mgt=1" 000 N·s
IN=50
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120821615225.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120821615225.gif)
If=50×10 N·s="500" N·s
F合=0,由I=Ft,可知选D.
![](http://thumb2018.1010pic.com/images/loading.gif)
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