运动学的定义

在物理学中，运动学是研究粒子或粒子系统的运动，而不考虑粒子的质量或引起粒子运动的力。

对位移、速度和加速度等量的研究属于物理学中运动学的范畴。

什么是取代(displacement)？

Displacement measures the difference between a particle’s initial and final position. If the position vector of the particle’s initial position, , is  and the position vector of the particle’s final position, , is  , then the displacement of the particle is given by:

.

如何计算位移

什么是速度(velocity)？

速度是位置相对于时间的变化率。定义为：

.

什么是加快(acceleration)？

加速度是速度相对于时间的变化率。定义为：

.

什么是一维运动学(one-dimensional kinematics)？

一维运动学是粒子沿直线运动的运动学，即在一个空间维度上。

Under one-dimensional kinematics in physics, we c***ider a particle moving along a straight line. We can derive equati*** of motion for the special case where the acceleration is c***tant. In deriving these equati*** of motion, we will assume that the particle is moving only in a straight line along the -axis.

If acceleration is uniform, then, over a given period of time , the average velocity   is given by , where   is the velocity of the particle at the beginning of the time period and is the velocity of the particle at the end of the time period. In this case, the total displacement, , is simply the product of the average velocity and time:

什么是二维运动学(two-dimensional kinematics)？

二维运动学涉及在平面上运动的粒子，即在两个空间维度上运动的粒子。

With two-dimensional kinematics in physics, in order to ****yse two-dimensional motion, we resolve all vector components into two directi*** which are perpendicular to each other (for instance, the – and  -axes on the Cartesian plane, or “vertical” and “horizontal” directi***). Motion along one of these directi*** is then independent of the motion along the other. C***equently, equati*** of motion can be applied to each of these directi*** separately.

For example, c***ider a cannonball shot off from the ground at an angle  to the horizontal. In the   -direction, the cannonball experiences a c***tant acceleration of   -9.81 m s-2. Horizontally, the acceleration is 0, assuming air resistance is negligible.

如何解决弹丸运动问题

工具书类

柯克比，L。答(2011). 物理是学生的同伴。接穗出版。

惠塔克，E。T(1904). 粒子分析动力学论著；刚体。剑桥大学出版社。