The sails are mounted at an angle or are given a slight twist, so that the forceofwind against them has two components, one of which, in the plane of the sails, causes rotation.
风叶有一个安装角或略有扭曲，因此可将吹来的风分解为两个分力，其中在风叶平面上的分力使风车旋转。
3
Because the leaves on a tree branch all grow at the same end of the branch, Eloy modeled the forceofwind blowing on a tree's leaves as a force pressing on the unanchored end of a cantilevered beam.