📚 Pre-U Edexcel Physics: Glossary & Mnemonics Guide | Pre-U Edexcel 物理：词汇术语速记指南
Mastering the terminology is the first step towards excelling in Pre-U Edexcel Physics. This guide breaks down key vocabulary across all major topics, pairing each term with a concise definition, a memorable mnemonic or learning trick, and a bilingual explanation to reinforce deep understanding. Use it to sharpen your recall and connect concepts with confidence.
掌握物理术语是攻克 Pre-U Edexcel 物理的第一步。本指南梳理了所有核心板块的关键词汇，每条术语都配有简明定义、巧记口诀或学习诀窍，并采用双语解释来强化深度理解。用它来打磨你的记忆力、从容串联概念吧。
1. Kinematics and Dynamics | 运动学与动力学
Displacement is the straight-line distance in a given direction from a fixed origin. It’s a vector, not to be confused with distance (a scalar). Think: ‘s’ in SUVAT is displacement, so always consider sign for direction.
位移是从固定原点沿某方向测量的直线距离。它是矢量，不要和路程（标量）混淆。记忆诀窍：SUVAT 里的 s 就是位移，永远要考虑方向的正负号。
Velocity is the rate of change of displacement. The phrase ‘velocity is speed with a direction’ helps; the gradient of a displacement-time graph gives velocity.
速度是位移的变化率。记住‘速度是带方向的速率’就行；位移-时间图像的斜率就是速度。
Acceleration time graph is a straight line, acceleration is constant. Remember: a = Δv/Δt or (v − u)/t.
加速度是速度的变化率。如果速度-时间图像是一条直线，加速度就是恒定的。公式：a = Δv/Δt 或 (v − u)/t。
2. Forces and Newton’s Laws | 力与牛顿定律
Newton’s First Law states that an object remains at rest or in uniform motion unless acted upon by a resultant force. Mnemonic: ‘Inertia keeps you going’ — objects resist changes to their motion.
牛顿第一定律指出，除非受到合外力作用，物体将保持静止或匀速直线运动。记住‘惯性让你继续’——物体会抵抗运动状态的改变。
Resultant force is the single force that has the same effect as all the forces acting on an object. Use free-body diagrams; sum vectors head-to-tail.
合外力指的是作用效果与所有实际作用力相同的那个单一力。画受力分析图，用矢量首尾相接法求和。
Newton’s Second Law is F = ma (resultant force = mass × acceleration). The mnemonic ‘FMA’ spells forward momentum: Force = Mass × Acceleration.
牛顿第二定律即 F = ma（合外力 = 质量 × 加速度）。记作‘FMA’——力量来自质量与加速度的乘积。
Newton’s Third Law: if body A exerts a force on body B, body B exerts an equal and opposite force on body A. These are of the same type and act on different bodies – never cancel.
牛顿第三定律：若物体 A 对 B 施加力，则 B 对 A 施加大小相等、方向相反的力。这对力属同种类型，作用在不同物体上——永远不会相互抵消。
3. Work, Energy and Power | 功、能与功率
Work done is the product of force and displacement in the direction of the force: W = F × s × cosθ. It’s measured in joules. ‘Work means energy transferred’ — when a force moves something, energy is shifted.
功是力与沿力方向位移的乘积：W = F × s × cosθ，单位是焦耳。记住‘功即能量的转移’——力移动物体，能量就发生了转移。
Kinetic energy ½mv². Only positive; depends on speed squared, so doubling speed quadruples KE. Mnemonic: ‘KE is key to motion’ — faster object, much more energy.
动能 KE = ½mv²。只有正值；取决于速度的平方，所以速度加倍，动能增至四倍。口诀：‘动能是运动之钥’——物体越快，能量大得多。
Gravitational potential energy nge near Earth’s surface = mgΔh. It’s a scalar and only depends on vertical height change.
重力势能变化在地表附近等于 mgΔh。它是标量，只取决于竖直高度的变化。
Power is the rate of doing work: P = W/t or P = Fv for constantvelocity motion. Unit: watt (W). ‘Power is how fast you work’.
功率是做功的快慢：P = W/t，或在匀速时 P = Fv。单位瓦特。记忆：‘功率就是你干活的快慢’。
4. Circular Motion and Gravitation | 圆周运动与引力
Angular velocity ω is the rate of change of angular displacement, ω = 2πf = 2π/T. Units: rad s⁻¹. Tip: ‘omega sweeps angles’.
角速度 ω 是角位移的变化率，ω = 2πf = 2π/T，单位弧度每秒。诀窍：‘omega 扫过角度’。
Centripetal force mv²/r = mrω². It is not a separate force but provided by tension, gravity, friction, etc.
向心力是维持圆周运动所需的指向圆心的合外力：F = mv²/r = mrω²。它并非额外力，而是由张力、引力、摩擦力等提供。
Gravitational field strength Newton’s law of gravitation: F = −GMm/r² (the minus sign reminds of attractive direction).
引力场强度 g 是单位质量所受的引力。万有引力定律：F = −GMm/r²（负号提醒方向是吸引）。
Kepler’s Third Law states that T² ∝ r³ for planetary orbits (under central inverse-square force). Useful for comparing orbits.
开普勒第三定律指出在中心平方反比引力作用下，行星轨道有 T² ∝ r³。用于比较不同轨道很有用。
5. Thermal Physics | 热物理学
Internal energy is the sum of random kinetic and potential energies of particles. It increases when temperature rises or phase changes to more disordered state. Mnemonic: ‘In U we trust’ – internal energy as sum of K.E. and P.E.
内能是粒子无规则动能与势能的总和。温度上升或物态变得更无序时内能增加。记忆：‘U 里藏着 KE + PE’。
Specific heat capacity c: energy to raise temperature of 1 kg by 1 K: Q = mcΔθ. ‘C is how stubborn the substance is to heat’.
比热容 c：使 1 kg 物质温度升高 1 K 所需能量：Q = mcΔθ。‘c 反映了物质抗拒升温的固执程度’。
Specific latent heat rature change: Q = mL. Latent heat of fusion (solid-liquid) and vaporisation (liquid-gas).
比潜热 L：温度不变时单位质量吸收的能量：Q = mL。分为熔化潜热（固-液）和汽化潜热（液-气）。
Ideal gas equation kinetic theory gives pV = ⅓Nmc²rms. Link: temperature measures average kinetic energy (½m
理想气体方程：pV = nRT，其中 n 为摩尔数，T 用开尔文。微观上有 pV = NkT，由分子动理论得 pV = ⅓Nmc²rms。关键：温度度量平均动能（½m
6. Simple Harmonic Motion | 简谐运动
SHM definition d : acceleration is proportional to displacement from equilibrium and always directed towards equilibrium: a = −ω²x. The minus sign does the trick: restoring.
简谐运动定义：加速度与相对平衡位置的位移成正比，且总指向平衡位置：a = −ω²x。负号是关键——代表回复性。
Displacement in SHM: x = A cos(ωt) or A sin(ωt) depending on start. ‘Starting from max? Use cos. Starting from equilibrium? Use sin.’
简谐运动位移：x = A cos(ωt) 或 A sin(ωt)，取决于起始条件。诀窍：‘从最大开始用 cos，从平衡位置开始用 sin’。
Velocity maximum vₘₐₓ = ωA; acceleration maximum aₘₐₓ = ω²A. Remember: ‘velocity fast at centre, acceleration strongest at extremes’.
最大速度 vₘₐₓ = ωA；最大加速度 aₘₐₓ = ω²A。口诀：‘中心速度最大，端点加速度最强’。
Energy in SHM and potential interchanging. The graph of Eₖ and Eₚ against displacement is a key exam favourite.
简谐运动的能量：总能量 = ½mω²A²，动能与势能互相转化。Eₖ 和 Eₚ 随位移变化的图像是考试热点。
7. Waves and Optics | 波与光学
Transverse vs longitudinal: transverse – oscillations perpendicular to energy transfer (light, water); longitudinal – oscillations parallel to energy transfer (sound). Mnemonic: ‘T’ for perpendicular looks like a cross.
横波与纵波：横波——振动垂直于能量传递方向（光、水波）；纵波——振动平行于能量传递方向（声波）。记忆：‘横’字里有‘黄’，黄草头左右分——垂直感。
Wave speed v = fλ. Use in all contexts: electromagnetic spectrum, sound, waves on strings. ‘Frequency times wavelength gives you speed’.
波速 v = fλ。所有波都适用：电磁谱、声波、弦上波。‘频率乘波长就是速度’。
Refraction and Snell’s Law l internal reflection occurs when angle of incidence exceeds critical angle (sin C = 1/n).
折射与斯涅尔定律：n₁ sin θ₁ = n₂ sin θ₂。折射率 n = c/v。当入射角大于临界角时发生全内反射（sin C = 1/n）。
Interference: constructive when path difference = nλ; destructive when path difference = (n + ½)λ. ‘In phase adds up, out of phase cancels’.
干涉：路程差为 nλ 时加强；路程差为 (n + ½)λ 时削弱。‘同相相加，反相相消’。
8. Electricity and Circuits | 电学与电路
Current , the rate of flow of charge. Conventional current is opposite to electron flow. Remember: ‘Current is flow, not the electron itself’.
电流 I = ΔQ/Δt，是电荷的流动速率。约定电流方向与电子流动方向相反。别忘了：‘电流是流动，不是电子本身’。
Ohm’s Law V = IR for constant temperature. Resistance R = ρL/A (resistivity times length over area). ‘V is the push, I is what flows, R is the opposition’.
欧姆定律：恒温时 V = IR。电阻 R = ρL/A（电阻率乘长度除以截面积）。‘V 是推力，I 是流量，R 是阻滞’。
Kirchhoff’s laws: Current law – sum of currents into a junction = sum out. Voltage law – sum of emfs = sum of p.d.s around a closed loop. ‘What goes in must come out; what goes up must come down’.
基尔霍夫定律：电流定律——流入节点的电流之和等于流出之和。电压定律——闭合回路中电动势之和等于电势降之和。‘进多少出多少，升多少降多少’。
Potential divider: Vₒᵤₜ = Vᵢₙ × (R₂/(R₁ + R₂)). Used in sensor circuits with LDR or thermistor. Mnemonic: ‘The output takes the fraction of its own resistance’.
分压器：Vₒᵤₜ = Vᵢₙ × (R₂/(R₁ + R₂))。用于含有光敏电阻或热敏电阻的传感器电路。记忆：‘输出电压按自身电阻占的比例来拿’。
9. Electromagnetic Induction | 电磁感应
Magnetic flux Φ = BA cosθ, unit weber (Wb). ‘Flux is the amount of field passing through an area’.
磁通量 Φ = BA cosθ，单位韦伯。‘通量就是穿过某个面积的磁场量’。
Faraday’s Law Φ/dt. Lenz’s Law (the minus sign) means the induced current opposes the change causing it. ‘Induced current fights back’.
法拉第定律：感应电动势 = 磁链变化率的负值，ε = −N dΦ/dt。楞次定律（负号）表示感应电流反抗引起它的变化。‘感应电流总要打回去’。
Faraday’s disk and moving conductor ular to B at speed v, induced emf = BLv. Derived by considering area swept out per second.
法拉第圆盘与运动导体：长 L 的导体棒以速度 v 垂直于 B 运动时，感应电动势 = BLv。可根据每秒扫过的面积推出。
Transformer equation: Vₛ/Vₚ = Nₛ/Nₚ. For an ideal transformer, power in = power out, so Iₛ/Iₚ = Nₚ/Nₛ. ‘Step up voltage, step down current’.
变压器公式：Vₛ/Vₚ = Nₛ/Nₚ。理想变压器输入功率等于输出功率，所以 Iₛ/Iₚ = Nₚ/Nₛ。‘升压就降流，降压就升流’。
10. Fields: Electric, Magnetic, Gravitational | 场：电场、磁场、引力场
Gravitational field F/m. For a point mass, g = GM/r². Field lines are radial and inward. Potential V = −GM/r. ‘Gravity is always attractive, potential negative’.
引力场：g = F/m。点质量场强 g = GM/r²。场线呈径向向内。引力势 V = −GM/r。‘引力总是吸引，势取负值’。
Electric field field between parallel plates: E = V/d. Direction: field lines from positive to negative. ‘E is force per unit charge’.
电场：E = F/q。点电荷电场 E = kQ/r²。平行板间匀强电场：E = V/d。方向：场线从正到负。‘E 是单位电荷所受的力’。
Magnetic field of a current Hand Rule for motor effect: Force F = BIL sinθ. Right hand grip rule for field direction.
电流的磁场：长直导线，B = μ₀I/(2πr)；螺线管，B = μ₀nI。左手定则判定安培力（电动机效应）：F = BIL sinθ。右手螺旋定则判断磁场方向。
11. Quantum and Nuclear Physics | 量子与核物理
Photon energy: E = hf = hc/λ. The idea that light comes in packets explains photoelectric effect. ‘Photon energy matches the frequency’
光子能量：E = hf = hc/λ。光以量子形式传播，这一概念解释了光电效应。‘光子能量与频率成正比’。
Photoelectric effect φ. Stopping potential eVs = Kₘₐₓ. Key graph: Kₘₐₓ versus f is straight line with slope h.
光电效应：只有当光子能量大于逸出功 φ 时才发射电子。最大动能 Kₘₐₓ = hf − φ。遏止电势 eVs = Kₘₐₓ。关键图像：Kₘₐₓ-f 图像是一条斜率为 h 的直线。
Wave-particle duality: de Broglie wavelength λ = h/p. Electrons can diffract; this confirms their wave nature. ‘Moving particles have a wavelength’.
波粒二象性：德布罗意波长 λ = h/p。电子能产生衍射，证实其波动性。‘运动的粒子有波长’。
Nuclear notation: ᴬᙆ nucleon number. Activity A = −dN/dt = λN, where λ is decay constant. Half-life Tₕ = ln2/λ.
核符号：ᴬᙆX，Z 为质子数，A 为核子数。活度 A = −dN/dt = λN，其中 λ 为衰变常数。半衰期 Tₕ = ln2/λ。
12. Key Skills and Units | 关键技能与单位
SI Base units: metre (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), candela (cd). All other units are derived. Always check dimensional consistency: ‘If your formula doesn’t give the right units, it’s wrong’.
国际基本单位：米(m)、千克(kg)、秒(s)、安培(A)、开尔文(K)、摩尔(mol)、坎德拉(cd)。其余均为导出单位。永远要核查量纲是否一致：‘公式单位不对，它就肯定不对’。
Scalars vs vectors: Scalars have magnitude only (mass, energy, time). Vectors have magnitude and direction (velocity, force, momentum). Adding vectors requires triangle/parallelogram law, not simple arithmetic.
标量与矢量：标量只有大小（质量、能量、时间）。矢量有大小和方向（速度、力、动量）。矢量相加必须用三角形或平行四边形法则，不能直接代数相加。
Significant figures and uncertainties: quote answers to an appropriate number of significant figures; absolute and percentage uncertainties combine in calculations. ‘Add percentage uncertainties when multiplying or dividing’.
有效数字与不确定度：答案应给出合适的有效数字位数；计算中绝对不确定度和相对不确定度需要组合。‘乘除时百分比不确定度相加’。
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