第二章点的运动学6.ppt

1 1 证明 是沿着主法线方向,即 。 Show is directed to the direction of the principal normal, i.e. Proof: 证明: 由于点由外向内运动,曲率半径? 越来越小,所以加速度越来越大。而速度 v =常数,故点运动快慢不变。 The radius of curvature ? becomes smaller as M moves from the outside to the inside and, consequently, its acceleration becomes bigger and bigger. Since v =const it moves with a constant velocity. 1 1 asdfa * Theoretical mechanics ①Kinematics ①运动学 ②Objects of kinematics ②运动学研究的对象 Basic concepts of kinematics 运动学的一些基本概念 The science of the relation between a given motion of an object and time. in which only the geometrical characteristics of the motion such as trajectories, velocities and accelerations, are studied, but not the reasons for the motion considered. 是研究物体在空间位置随时间变化的几何性质的科学。 (包括:轨迹，速度，加速度等)不考虑运动的原因。 ①Develops the methods for describing mechanical motions. ②Establishes the relations between the variables related to motion. ①建立机械运动的描述方法 ②建立运动量之间的关系 Introduction 引 言 ③运动学学习目的 ③Why we study it? ④运动是相对的 ④Relativity of motion ⑤瞬时、时间间隔 ⑤Instant of time, interval of time ⑥运动分类 ⑥Classification of motions 为后续课打基础及直接运用于工程实际。 Foundations for the following courses and and direct applications in engineering practice. 参考体(物);参考系;静系;动系。 Reference object; frame of reference system, frame of static reference System, moving frame of reference system. 1)点的运动 2)刚体的运动 1) Motion of a particles . 2)Motion of a rigid body . Theoretical mechanics §6–1 Description of the motion of a particle using a vector of position §6–1 点的运动矢量分析方法 Chapter 6 Kinematics of a Particle 第六章 点的运动学 § 6–2 Description of the motion of a particle using rectangular coordinates §6–2 点的运动的直角坐标法 § 6–3 Description of the motion of a particle using natural coordinates §6–3 点的运动的自然坐标法 1 1. Equation of motion, trajectory (path) 一.运动方程，轨迹 §6-1 Description of the motion of a particle using a vector of position §6-1 点的运动矢