从变质量物体的运动谈起

On the Moment of Variable Object

牛顿运动定律以及由牛顿第二定律推导出的动量定理、动量矩定理、动能定理,只适用于宏观低速的情况下,而且在运动的过程中,物体的质量是恒定不变的。然而在宏观低速的情况下,我们会遇到许多变质量物体运动的问题,在此情况下,牛顿运动定律以及由此推导出的三条基本定理将要做一定的修改,其表达式是不一样的。

The Law of Momentum, Law of Moment of Momentum and Law of Kinetic Energy, which are derived based on Newton＇ s Laws of Motion and Newton＇s Second Law, are only adapted to the situation of macroscopical low- speed, but the mass of object is invariable during the course of motion. However, we may meet some problems. In this case, Newton ＇ s Laws of Motion and the above three laws need to be amended. The thesis discusses the expressions of the above three laws in the case that the variable object is in movement.