(3)惯性参考系这一名称的暗示一在这些特 殊的参考系中,牛顿定律成立 Figure 2-1 A test to tell a reference frame is inertial or not 问题:试着给出一些例子来说明,为什么一个参考系 是或不是惯性系
⑶惯性参考系这一名称的暗示 — 在这些特 殊的参考系中, 牛顿定律成立. 问题: 试着给出一些例子来说明, 为什么一个 参考系 是或不是惯性系
Figure 2-1 A test to tell a reference frame is inertial or not 火星表面的运动 从地球到火星 结论:??
火星表面的运动 从地球到火星 结论:??
2.牛顿第二定律 牛顿第二运动定律可总结为一个简单的矢 量方程: F=m2外力 It is expressed in word as: A external force acting on a body produces an acceleration which is in the direction of the force and has a magnitude inversely proportional to反比于 the mass of the body
2. 牛顿第二定律 牛顿第二运动定律可总结为一个简单的矢 量方程： It is expressed in word as: A external force acting on a body produces an acceleration which is in the direction of the force and has a magnitude inversely proportional to反比于the mass of the body. F ma 外力 = (2-1)
To understand Newton's second law, we must note what physical meanings it includes (1Newton's second law is valid (有效) only in particles or the obiects that can be regarded as particle particle 可看成
To understand Newton’s Second Law, we must note what physical meanings it includes. (1)Newton’s second law is valid （有效） only in particles or the objects that can be regarded as particle. particle 可看成
(2)If several external forces F,E, F b.,... act simultaneously(同时) on a body,is acceleration is the sum of these produced by a single force given by
(2) If several external forces ... ... act simultaneously （ 同 时 ） on a body, its acceleration is the sum of these produced by a single force given by F F ,F , F F F a