如图,一抛物线形状的光滑导轨固定在竖直平面内,
O为抛物线导轨的顶点,
O点离地面的高度为
h ,
A、
B两点相距2
h , 轨道上套有一个小球M,小球M通过轻杆与光滑地面上的小球N相连,两小球的质量均为
m , 轻杆的长度为2
h。现将小球M从距地面竖直高度为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmfrac%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E4%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3Cmi%3Eh%3C%2Fmi%3E%3C%2Fmath%3E)
处静止释放,下列说法正确的是( )
![](http://tikupic.21cnjy.com/2024/05/31/cf/04/cf04bf3fc3331f8c90b83ae88214540a.png)
- A、小球M即将落地时,它的速度方向与水平面的夹角为30°
- B、小球M即将落地时,它的速度方向与水平面的夹角为60°
- C、从静止释放到小球M即将落地,轻杆对小球N做的功为
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmfrac%3E%3Cmrow%3E%3Cmi%3Em%3C%2Fmi%3E%3Cmi%3Eg%3C%2Fmi%3E%3Cmi%3Eh%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3C%2Fmath%3E)
- D、从静止释放到小球M即将落地,轻杆对小球N的冲量大于
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3Em%3C%2Fmi%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmfrac%3E%3Cmrow%3E%3Cmi%3Eg%3C%2Fmi%3E%3Cmi%3Eh%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3C%2Fmath%3E)