For a ball rolling across the floor, that outside force could be the friction between the ball and the floor, or it could be the toddler that kicks the ball in another direction.
对于一个在地面上滚动的球而言，外力可能是球与地面之间的摩擦力或者幼童相反方向踢球产生的力。
2
The double moved cylinder pretreating-machine clears away the nonidentical substance adhering to the surface of lump-shaped objects via centrifugal rollingfriction collision.
双动滚笼式螺旋预处理机是通过对块状物体的离心滚动摩擦碰撞，清除其表面的非同质附着物。
3
If rollingfriction is substituted for sliding friction, the friction will be considerably reduced.