题目内容
A、B两物体的质量之比为ma∶mb=1∶2.用质量不计的弹簧把它们连接起来,放在光滑水平面上,A物体靠在固定板上,如图所示.用力向左推B物体,压缩弹簧,当外力做功为W时,突然撤去外力,从A物体开始运动以后,弹簧弹性势能的最大值是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241141209591456.jpg)
A.W/3 B.W/2 C.2W/3 D.W
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241141209591456.jpg)
A.W/3 B.W/2 C.2W/3 D.W
A
由功能关系知撤去外力时,系统的机械能为W,A物体开始运动后,A、B及弹簧这一系统的机械能守恒,动量守恒,且A、B具有相等速度时,弹簧弹性势能最大.
则由
mBv12="W " ①
mBv1="(mA+mB)v " ②
mBv12-
(mA+mB)v2="Ep " ③
由①②③得Ep=
W.
则由
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114120975225.gif)
mBv1="(mA+mB)v " ②
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114120975225.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114120975225.gif)
由①②③得Ep=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114121115219.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目