宇宙速度是宇宙航行的重要参数。现行高中物理教材在介绍宇宙速度时一般只推导了第一宇宙速度,而没有推导第二宇宙速度和第三宇宙速度,本文介绍第二宇宙速度和第三宇宙速度的推导。一、第二宇宙速度的推导设入造星体的质量为m,地球的质量和半径分别为M_地和R_地,地球表面的重力加速度为g。把从地球表面至无穷远处的距离等分成无数小段、ab、bc、cd……,各等分点关于地心对应的半径分别为r_1、r_2、r_3……,如图1所示。由于每小段ab、bc、cd……极小,这一小段上的引力可以认为不变。因此,把人造星体从地表a送到b时,克服引力所做的功为 Cosmic speed is an important parameter of cosmic voyage. The current high school physics textbook only generalizes the first universe velocity when introducing the universe velocity, but does not derive the second universe velocity and the third universe velocity. This article introduces the derivation of the second universe velocity and the third universe velocity. I. The Second Universe Velocity Derivation The mass of the star-forming body set to m, the mass and radius of the Earth, is M_l and R_l, respectively, and the gravitational acceleration on the Earth’s surface is g. The distance from the surface of the earth to infinity is divided into numerous small sections, ab, bc, cd, ..., and the radii corresponding to the geocentric centers of the respective points are r_1, r_2, r_3, ... respectively, as shown in Figure 1. Since each ab, bc, cd ... is extremely small, the gravitational force on this small segment can be considered unchanged. Therefore, when the artificial star is sent from surface a to b, the work done to overcome the gravitational force is done