论文部分内容阅读
用正交分解法求解力学题通常要建立坐标轴.从理论上说,坐标轴的建立是可以任意的,但是,坐标轴选得是否巧妙,往往会影响解题的繁简.现例谈在三种情况下怎样巧选坐标轴. 一、在牛顿第二定律应用问题中 在此类问题中,为减少矢量的分解,建立直角坐标,确定x轴方向时一般有两种方法: 1.分解力而不分解加速度,此时应规定加速度方向为x轴的正方向. 例1 质量为m的物体放在倾角为α的斜面上,物体和斜面间的动摩擦因数为μ,如沿水平方向加一个力F,使物体沿斜面向上以加速度a做匀加速运动,如图1所示,求F的大小?
Orthogonal decomposition method for solving mechanical problems usually establishes the coordinate axes. Theoretically speaking, the establishment of coordinate axes can be arbitrary, but the selection of coordinate axes is ingenious and often affects the complexity of the problem. How to choose the coordinate axes in three situations. First, in the problem of Newton’s second law application, in order to reduce vector decomposition and establish orthogonal coordinates, there are generally two methods to determine the x-axis direction: 1. Decomposition Force does not decompose the acceleration. At this time, the direction of acceleration should be defined as the positive direction of the x-axis. Example 1 An object with a mass of m is placed on an inclined plane with an inclination of α, and the dynamic friction coefficient between the object and the inclined plane is μ, as in the horizontal direction. A force F, so that the object along the inclined surface with acceleration a uniform acceleration movement, as shown in Figure 1, find the size of F?