本刊2003年第9期刊登了《物块速度垂直于悬线的数学证明》一文,文中用严格的高等数学方法证明了:绳不断地缠绕在光滑的平面凸曲线C上的过程中,绳端物块速度总是垂直于绳(如图1).读后感觉证明过程较繁琐,物理意义也不太明了.本文将给出一个物理意义明了、简捷的证明. The article “Mathematical Proof of Block Velocity Perpendicular to Suspension Lines” was published in the 9th issue of the magazine in 2003. It is proved in the article that strict high-grade mathematics proves that the rope is continuously wound on the smooth plane convex curve C. The velocity of the end piece is always perpendicular to the rope (see Figure 1). The post-reading proof process is cumbersome and the physical meaning is not clear. This article will give a clear, simple proof of physical meaning.