📚 A-Level CAIE Engineering: Formula & Theorem Quick Reference Handbook | A-Level CAIE 工程：公式定理速查手册
This quick reference handbook summarises the essential formulae, principles and theorems required for the Cambridge International AS & A Level Engineering syllabus. Use it alongside past paper practice, and always write the formula before substituting values.
本速查手册总结了剑桥国际 AS 与 A Level 工程课程所需的核心公式、原理和定理。建议配合真题练习使用，并在代入数值前先写出公式。
1. SI Units, Prefixes and Derived Units | 国际单位制、词头与导出单位
Begin every calculation by converting all data into consistent SI units. This prevents systematic errors in equations such as F = ma, which requires mass in kg and acceleration in m s⁻².
每次计算前，应把所有数据转换为一致的 SI 单位。这样可以避免 F = ma 等方程因单位不统一而产生系统性错误，该方程要求质量用 kg、加速度用 m s⁻²。
| Prefix | Factor | Example |
|---|---|---|
| giga (G) | 10⁹ | 1 GHz = 10⁹ Hz |
| mega (M) | 10⁶ | 1 MPa = 10⁶ Pa |
| kilo (k) | 10³ | 1 kN = 10³ N |
| centi (c) | 10⁻² | 1 cm = 10⁻² m |
| milli (m) | 10⁻³ | 1 mm = 10⁻³ m |
| micro (μ) | 10⁻⁶ | 1 μm = 10⁻⁶ m |
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