辨析水平面与切平面

Differentiation Between Horizontal Plane and Tangent Plane

文献[1]的作者认为:若把地球看作均匀理想的球体,则无法解释重力方向与引力方向的不一致;好在地球是一个赤道略鼓的椭球体,成功地解决了竖直向下不指向地心的问题。但是,此解释存在瑕疵,通过讨论地面某处切平面与水平面的区别,给出更合理的解释。

The author of reference[1]explained that it can not explain the unconsistence of directions of gravity and attractive forces were not consistent if the earth is taken as a uniform ideal sphere.Fortunately,the earth is an ellipsoid with a slight bulge in the equator,which successfully solves the problem of pointing vertically downward instead of toward the center of the earth.But this explanation has its defects,a more reasonable explanation is provided by discussing the difference between the tangent plane and the horizontal plane on the ground.