📚 A-Level Physics: June 2018 Insert 2 Formula Derivations | A-Level 物理：2018年6月插页2公式推导
In the June 2018 AQA A-level Physics examination, Insert 2 provided a handy reference of essential formulae covering mechanics, waves, fields, nuclear physics and thermal physics. However, simply memorising them is not enough; understanding their derivations sharpens problem-solving skills and deepens physical insight. This article walks you through the derivations of eight key formulas from that insert, pairing each step in English and Chinese to aid bilingual learners.
在2018年6月AQA A-Level物理考试中，插页2提供了涵盖力学、波、场、核物理和热物理的核心公式表。然而，单纯记忆公式远远不够；理解公式的推导过程能提升解题能力，加深物理直觉。本文带你逐步推导该公式表中的八个关键公式，每步均以中英双语对照，帮助你深入学习。
1. Centripetal Acceleration: a = v²/r | 向心加速度 a = v²/r 推导
Consider an object moving at constant speed v along a circular path of radius r. Although its speed is constant, the direction of velocity changes continuously, resulting in an acceleration towards the centre.
考虑一个物体以恒定速率 v 沿半径为 r 的圆周运动。虽然速率不变，但速度方向时刻改变，因此存在指向圆心的加速度。
ty vectors at A and B; they have equal magnitude v but different directions, separated by the same angle Δθ.
在很短的时间间隔 Δt 内，物体从 A 点运动到 B 点，经过的弧长 Δs = vΔt。相应的圆心角 Δθ = Δs/r。分别画出 A 点和 B 点的速度矢量，它们大小均为 v，但方向不同，夹角同样为 Δθ。
The change in velocity Δv is the vector difference vB – vA magnitude of acceleration is a = Δv/Δt = (v/r)(Δs/Δt) = v²/r, directed towards the centre.
速度的变化
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