题目内容
物体静止在光滑水平面上,先对物体施加一水平向右的恒力F1,经时间t后撤去F1,立即再对它施加一水平向左的恒力F2,又经时间3t后物体回到出发点,在这一过程中,F1、F2分别对物体做的功W1、W2间的关系是( )
A.W1∶W2=1∶1 | B.W1∶W2=2∶3 | C.W1∶:W2=9∶5 | D.W1∶W2=9∶7 |
D
试题分析:令恒力F1作用t后物体的速度为v1,恒力F2又作用2t后物体的速度为v2,所以物体在恒力F1作用t后物体的位移为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340319591.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340334801.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340350430.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340381574.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340412809.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340428937.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340459693.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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