流行观点认为,刚体在斜面上作纯滚动,静摩擦力起着将平动动能转换成转动动能的作用。本文通过对固定点使用动量矩定理,证明了加速转动的是一力偶矩。刚体转动动能的增量来源于该力偶矩的功,实质是重力所作功的一部分。静摩擦力所起的作用仅是提供了形成该力偶的条件,但并不直接参与能量的转换。 Pop point of view that the rigid body in the bevel for pure rolling, static friction plays a translational kinetic energy into rotational kinetic energy role. In this paper, by using the moment of momentum theorem for fixed points, it is proved that the moment of acceleration is a moment of merit. The increment of rigid body rotation kinetic energy comes from the work of this moment, which is essentially a part of the work done by gravity. Static friction plays a role only to provide the conditions for the formation of the couple, but not directly involved in the conversion of energy.