- goodpatrickLv 51 十年前最愛解答
A wheel is a circular device capable of rotating on its axis, facilitating movement or transportation or performing labour in machines. A wheel together with an axle overcomes friction by facilitating motion by rolling. Common examples are found in transport applications. More generally the term is also used for other circular objects that rotate or turn, such as a Ship's wheel and flywheel.
The force bearing on the axle has an eccentricity e with the point of contact to the rolling surface and exerts a moment about the contact point