📚 AQA A Level Physics Insert Unit 2 January 2021 | AQA 物理 A Level 第二单元资料插页（2021 年 1 月）
The AQA A Level Physics Unit 2 insert is a compact data and formulae booklet supplied in the exam. It covers mechanics, materials and waves. Using it quickly and accurately can save time, reduce recall errors and earn method marks in calculations, even when the final answer slips.
AQA 物理 A Level 第二单元资料插页是考试中随卷提供的数据与公式小册子，涵盖力学、材料与波动。快速并准确地使用它可以节省时间、减少记忆错误，并在计算题中获得步骤分，即使最终答案算错也一样拿分。
1. What the Insert Contains | 资料插页包含什么
The insert opens with fundamental constants and unit conversions relevant to the paper. It then groups equations by topic: motion, forces, energy, materials and waves. You are expected to select the correct equation without being told which one to use.
插页开头列有与试卷相关的基本常数和单位换算，然后按主题分组给出公式：运动、力、能量、材料和波动。题目不会提示你使用哪一条公式，因此你需要自行选择。
Do not treat the insert as a replacement for learning definitions. AQA questions often ask you to state the meaning of a symbol or explain the physical conditions under which an equation is valid.
不要将插页当作学习定义的替代品。AQA 题目经常要求你说明某个符号的含义，或解释某一公式成立的物理条件。
The booklet is identical in every session apart from the cover page, so the January 2021 insert is the same list of equations and constants you will meet in any other sitting. That makes it a legitimate revision checklist rather than a one-off exam accessory.
除封面外，每次考试的插页内容完全相同，因此 2021 年 1 月的插页与你在任何其他考季拿到的公式与常数清单一致。这使得它完全可以作为复习清单，而不是一次性的考场附属品。
Print a copy and keep it beside you for every past paper you attempt. Within a few weeks you will know its layout by heart, and that familiarity is exactly what saves minutes under exam pressure.
建议打印一份，并在做每一套真题时放在手边。几周之后你就能熟记它的排版布局，而这种熟悉感正是考场上节省时间的关键。
2. Fundamental Constants and Data | 基本常数与数据
⁻¹ or m s⁻², and the speed of light c = 3.00 × 10⁸ m s⁻¹ where relevant to wave questions.
使用前请先核对重力场强度的数值。插页通常给出 g = 9.81 N kg⁻¹ 或 m s⁻²，并在与波动相关的题目中给出光速 c = 3.00 × 10⁸ m s⁻¹。
| Quantity | Symbol | Value |
| Acceleration due to gravity | g | 9.81 m s⁻² (or N kg⁻¹) |
| Speed of light in vacuum | c | 3.00 × 10⁸ m s⁻¹ |
The symbols printed in the insert are the symbols you should use in your working. If you choose a different letter for a quantity, define it clearly in words or the examiner may not be able to follow your method.
插页中印刷的符号就是你在解题过程中应当使用的符号。如果你为某个物理量另选字母，请用文字明确标注其含义，否则考官可能无法理解你的解题思路。
Never round a constant before the end of a calculation. Carry the full 9.81 through your working and round only the final answer, usually to two or three significant figures.
不要在计算结束前对常数取整。请把 9.81 的完整数值带入运算，只在最后对答案取两到三位有效数字。
3. Units, Prefixes and Conversions | 单位、前缀与换算
Always convert prefixes such as cm, mm, km, g and cm² before substituting numbers. A common error is to use centimetres in equations that expect metres, which changes the answer by a factor of 100.
代入数值前，请务必换算掉 cm、mm、km、g 和 cm² 等单位前缀。常见错误是在公式要求使用米时仍使用厘米，这会让答案相差 100 倍。
| Prefix | Symbol | Factor |
| pico | p | 10⁻¹² |
| nano | n | 10⁻⁹ |
| micro | μ | 10⁻⁶ |
