運動學的定義

在物理學中，運動學是研究粒子或粒子系統的運動，而不考慮粒子的質量或引起粒子運動的力。

對位移、速度和加速度等量的研究屬於物理學中運動學的範疇。

什麼是取代(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:

.

如何計算位移

什麼是速度(velocity)？

速度是位置相對於時間的變化率。定義為：

.

什麼是加快(acceleration)？

加速度是速度相對於時間的變化率。定義為：

.

什麼是一維運動學(one-dimensional kinematics)？

一維運動學是粒子沿直線運動的運動學，即在一個空間維度上。

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:

什麼是二維運動學(two-dimensional kinematics)？

二維運動學涉及在平面上運動的粒子，即在兩個空間維度上運動的粒子。

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.

如何解決彈丸運動問題

工具書類

柯克比，L。答(2011). 物理是學生的同伴。接穗出版。

惠塔克，E。T(1904). 粒子分析動力學論著；剛體。劍橋大學出版社。