题目内容
如图甲所示,轻质弹簧的下端固定在水平面上,上端放置一小物体(物体与弹簧不连接),初始时物体处于静止状态。现用竖直向上的拉力F作用在物体上,使物体开始向上做匀加速直线运动,拉力F与物体位移x的关系如图乙所示(g=10m/s2),则下列结论正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250034481863078.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250034481863078.jpg)
A.物体与弹簧分离时,弹簧处于压缩状态 |
B.物体的质量为3 kg |
C.物体的加速度大小为5 m/s2 |
D.弹簧的劲度系数为7. 5 N/cm |
C
试题分析:初始,物体静止在弹簧上面,弹簧弹力与重力平衡,施加F后即为合力所以有
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003448202624.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003448233755.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003448248670.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003448264570.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003448280612.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003448311433.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003448326590.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003448342980.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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