📚 Components of Vectors | 矢量的分量
In CIE A-Level Physics, many quantities such as displacement, velocity, acceleration and force are vectors. A vector has both magnitude and direction, but it is often much easier to handle a vector by splitting it into two perpendicular components. This technique is central to mechanics, statics, projectile motion and fields.
在 CIE A-Level 物理中，位移、速度、加速度和力等许多物理量都是矢量。矢量既有大小又有方向，但若把一个矢量分解为两个互相垂直的分量，通常会使分析和计算更加简单。这一方法在力学、静力学、抛体运动和场的计算中都非常核心。
1. What is a Vector Component? | 什么是矢量分量
A component of a vector is the effect of that vector in a particular direction. Usually we choose two perpendicular directions, x and y, and write vector A as A = Ax + Ay, where Ax lies along the x-axis and Ay lies along the y-axis. Each component can be treated as a scalar if the direction is shown by a positive or negative sign.
矢量的分量是该矢量在某一特定方向上的作用效果。通常我们选择两个互相垂直的方向，即 x 和 y 方向，把矢量 A 写成 A = Ax + Ay，其中 Ax 沿 x 轴，Ay 沿 y 轴。如果方向用正负号表示，每个分量本身就可以当作标量处理。
In CIE papers, you will often see phrases such as ‘resolve the force into components parallel and perpendicular to the slope’. This means exactly the same as writing the vector as the sum of two perpendicular vectors. The original vector is the vector sum of its components.
在 CIE 试卷中，你常会看到“把力分解为平行和垂直于斜面的分量”这类表述。它的意思与把矢量写成两个互相垂直的矢量之和完全相同。原矢量就是其各分量的矢量和。
A component can be positive or negative depending on the chosen positive direction. For example, a vector pointing left may have a negative x-component even if its magnitude is positive.
根据所选正方向的不同，分量可以是正值或负值。例如，一个指向左方的矢量，即使其大小为正值，其 x 分量也可能是负值。
2. Resolving a Vector into Perpendicular Components |
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