题目内容
某人把原来静止于地面上的质量为2.0kg的物体向上提起1.0m,并使物体获得1.0m/s的速度,取g为10m/s2,则在此过程中( )
A.人对物体做功20J |
B.物体的机械能增加1.0J |
C.合外力对物体做功1.0J |
D.重力对物体做功20J |
C
试题分析:在此过程中,人做正功,重力做负功,设人对物体做功为W,根据动能定理得,
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025029351032.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002502951554.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002502982913.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002502998875.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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