📚 Year 8 CIE Physics: Quick Guide to Essential Vocabulary | Year 8 CIE 物理：核心词汇速记指南
Building a strong physics vocabulary is like collecting the keys to unlock every concept. In Year 8, you will meet words like 'force', 'energy', and 'current' that describe how the world works. This guide gives you clear definitions, easy memory tricks, and paired English–Chinese explanations to help you learn faster and remember longer.
建立扎实的物理词汇库就像收集打开每个概念的钥匙。在 Year 8，你会遇到像 "力"、"能量" 和 "电流" 这样的词，它们描述世界如何运作。本指南为你提供清晰的定义、简单的记忆技巧，以及英中对照解释，帮助你学得更快、记得更牢。
1. Forces and Motion | 力和运动
Force ct speed up, slow down, change direction, or change shape. Memory tip: think of the phrase 'F = ma' – Force equals mass times acceleration.
力 是推或拉，单位为牛顿 (N)。它可以让物体加速、减速、改变方向或改变形状。记忆法：联想公式 F = ma，力等于质量乘以加速度。
Friction is a force that opposes motion between two surfaces in contact. It can cause objects to slow down and produces heat. Tip: 'Friction' sounds like 'friction slows', reminding you it acts against sliding.
摩擦力 是接触面之间阻碍运动的力。它使物体减速并产生热量。提示：摩擦的 "摩" 可以联想 "磨擦阻碍"。
Gravity is the force of attraction between any two masses. On Earth, it pulls objects towards the centre of the planet, giving them weight. Remember: 'G' for 'ground' – gravity pulls you to the ground.
重力 是两个物体之间相互吸引的力。在地球上，它将物体拉向地心，使物体具有重量。记住：'重' 表示向下的拉力。
Mass (kg) is the amount of matter in an object, which stays the same everywhere. Weight (N) is the force of gravity on that mass, so it changes with location. Memory: mass is your 'stuff', weight is how heavy that stuff feels.
质量 (kg) 是物体所含物质的多少，处处相同。重量 (N) 是作用在该质量上的重力，因此会随位置变化。记忆：质量是 "物质的量"，重量是 "感觉到的轻重"。
Speed is how fast an object moves, with no regard to direction. Velocity is speed in a given direction. Tip: velocity starts with 'v' like 'vector', which has direction.
速率 是物体运动的快慢，不考虑方向。速度 是带有方向的速率。提示：速度的 "速" 加上方向才是速度。
average speed = total distance ÷ time taken
平均速率 = 总距离 ÷ 所用时间
Acceleration ws down, or changes direction. If the velocity change is Δv, then acceleration a = Δv ÷ t.
加速度 是速度变化的快慢。物体加速、减速或改变方向时都存在加速度。若速度变化量为 Δv，则加速度 a = Δv ÷ t。
2. Energy | 能量
Energy is the ability to do work, measured in joules (J). It cannot be created or destroyed, only transferred or transformed – the law of conservation of energy.
能量 是做功的本领，单位为焦耳 (J)。能量不能凭空产生或消失，只能转移或转化——这就是能量守恒定律。
Kinetic energy he object, the more kinetic energy it stores. Formula: Kinetic Energy = ½ × mass × speed².
动能 是物体因运动而具有的能量。物体越快、越重，动能越大。公式：动能 = ½ × 质量 × 速率²。
Gravitational potential energy is energy stored in an object because of its height above the ground. A raised hammer has more potential energy to do work when it falls. Think: 'potential' means 'stored possibility'.
重力势能 是物体因离地高度而储存的能量。举高的锤子落下时能做更多功。记忆：'势' 表示 '储存的态势'。
Thermal energy is the total kinetic energy of particles in a substance. It flows from hotter to cooler objects. Also called heat energy.
热能 是物质内粒子动能的总和，从高温物体流向低温物体。也叫热量。
Chemical energy is stored in fuels, food, and batteries. It is released during chemical reactions, such as burning or digestion. Tip: think of 'chemical bonds' as tiny springs holding energy.
化学能 储存在燃料、食物和电池中，在化学反应时释放。提示：把化学键想象成储存能量的小弹簧。
Light energy travels in straight lines as waves and can be seen by our eyes. Sound energy travels as vibrations through a medium. Electrical energy is carried by moving charges in a circuit.
光能 以波的形式沿直线传播，可被眼睛看到。声能 通过介质振动传播。电能 由电路中运动的电荷携带。
3. Work and Power | 功和功率
Work done ovement, work = force × distance, measured in joules. No movement means no work in physics – even if you feel tired!
做功 发生在力使物体移动时。若力与运动方向相同，功 = 力 × 距离，单位焦耳。如果没有移动，物理上就没有做功——即使你感到累！
Power is the rate of doing work, or how quickly energy is transferred. It is measured in watts (W). One watt equals one joule per second. A powerful machine does the same work in less time.
功率 是做功的快慢，即能量转移的速率，单位为瓦特 (W)。1 瓦特 = 1 焦耳/秒。大功率机器在更短时间内完成相同的功。
Efficiency is wasted as heat or sound. Efficiency = (useful energy output ÷ total energy input) × 100%.
效率 比较有用输出能量与总输入能量，通常用百分数表示。效率高意味着较少能量被浪费为热或声音。效率 = (有用输出能量 ÷ 总输入能量) × 100%。
4. States of Matter | 物质状态
Solid: particles are tightly packed in a regular pattern and vibrate in fixed positions. Solids have a definite shape and volume. Think of soldiers standing to attention – they can shake but not move around.
固体：粒子紧密规则排列，在固定位置振动。固体有确定的形状和体积。想象立正的士兵——可以晃动但不能自由走动。
Liquid: particles are close together but can slide past each other. Liquids have a fixed volume but take the shape of their container. Picture a crowded dance floor – people stay near but can move around.
液体：粒子紧密排列但可以相互滑动。液体有固定体积，但形状随容器而变。想象拥挤的舞池——人们彼此靠近但能移动。
Gas: particles are far apart and move randomly at high speed. Gases have no fixed shape or volume and can be compressed easily. Like bees flying freely in a large garden.
气体：粒子相距很远，高速随机运动。气体没有固定形状和体积，容易被压缩。像在宽阔花园中自由飞舞的蜜蜂。
Melting is changing from solid to liquid (heat added). Freezing is liquid to solid (heat removed). Boiling and evaporation are liquid to gas. Condensation is gas to liquid.
熔化 是由固体变液体 (加热)；凝固 是液体变固体 (冷却)；沸腾 和 蒸发 是液体变气体；冷凝 是气体变液体。
Density s ÷ volume). A dense material packs a large mass into a small space. Objects less dense than water float; denser objects sink.
密度 是单位体积的质量（密度 = 质量 ÷ 体积）。密度大的材料在较小空间内集中很大质量。密度比水小的物体上浮，比水大的下沉。
5. Heat Transfer | 热传递
Conduction is the transfer of thermal energy through a solid by particle collisions. Metals are good conductors because their free electrons can carry energy quickly. Touch a hot spoon handle – energy conducts along it.
热传导 是通过粒子碰撞在固体中传递热能。金属是良导体，因其自由电子能快速传递能量。触摸热勺子柄——能量沿勺子传导过来。
Convection occurs in liquids and gases. Warmer, less dense regions rise, while cooler, denser regions sink, creating a convection current. Think of boiling water: hot water rises from the bottom.
热对流 发生在液体和气体中。较热、密度较小的区域上升，较冷、密度较大的区域下沉，形成对流循环。想象烧水时热水从底部上升。
Radiation is the transfer of energy by electromagnetic waves, mainly infrared. It can travel through a vacuum – that is how the Sun's energy reaches Earth. No particles are needed.
热辐射 是以电磁波 (主要是红外线) 传递能量。它可以在真空中传播——太阳的能量就是这样到达地球的，无需介质。
Conductor vs Insulator: conductors (e.g., copper, aluminium) allow heat to flow easily; insulators (e.g., wood, plastic, air) slow down heat transfer. A winter jacket works by trapping air, a good insulator.
导体与绝缘体：导体 (如铜、铝) 使热量容易流动；绝缘体 (如木头、塑料、空气) 减缓热传递。冬衣通过锁住空气（良好的绝缘体）来保暖。
6. Waves | 波
Wave: a disturbance that transfers energy from one place to another without transferring matter. Light waves, sound waves, and water ripples all carry energy.
波：将能量从一个地方传递到另一个地方的扰动，不传递物质。光波、声波和水波都携带能量。
Transverse waves: the vibrations are perpendicular to the direction of energy transfer. Light and water waves are transverse. Think of a rope shaken up and down – the wave travels along the rope.
横波：振动方向与能量传播方向垂直。光波和水波是横波。想象上下抖动绳子，波沿着绳子前进。
Longitudinal waves: the vibrations are parallel to the direction of energy transfer. Sound waves in air are longitudinal, with compressions and rarefactions. Like a spring being pushed and pulled.
纵波：振动方向与能量传播方向平行。空气中的声波是纵波，有疏密区域。像推拉弹簧一样。
Wavelength (λ) is the distance between two identical points on consecutive waves, e.g., crest to crest. Frequency (f) is the number of waves passing a point per second, measured in hertz (Hz).
波长 (λ) 是相邻两个波形相同点之间的距离，例如波峰到波峰。频率 (f) 是每秒通过某点的波数，单位为赫兹 (Hz)。
Amplitude is the maximum displacement of a wave from its rest position. In sound, amplitude relates to loudness; in light, it relates to brightness.
振幅 是波离开平衡位置的最大位移。在声音中，振幅与响度有关；在光中，与亮度有关。
wave speed = frequency × wavelength (v = f × λ)
波速 = 频率 × 波长 (v = f × λ)
7. Sound | 声音
Sound is produced by vibrations. The vibrating source pushes air particles, creating longitudinal pressure waves that travel to our ears. Tip: pluck a rubber band – you feel and hear the vibration.
声音 由振动产生。振动源推动空气粒子，形成纵波传至我们耳朵。提示：拨动橡皮筋——你既能感觉到也能听到振动。
Pitch depends on frequency. High frequency gives a high-pitched sound (e.g., a whistle); low frequency gives a low-pitched sound (e.g., a drum). 'Pitch' rhymes with 'rich' – a rich soprano sings high notes.
音调 取决于频率。频率高则音调高 (如哨声)；频率低则音调低 (如鼓声)。 '音调' 高的像女高音，低的像男低音。
Loudness depends on amplitude. A larger amplitude makes a louder sound. Shout harder, and the vocal cords vibrate with bigger amplitude.
响度 取决于振幅。振幅越大，声音越响。用力喊叫时，声带振幅增大。
Echo is a reflected sound wave. It arrives after the original sound if the reflecting surface is far enough. Ultrasound uses high-frequency sound beyond human hearing, for scanning or cleaning.
回声 是反射回来的声波。若反射面足够远，回声会在原声之后到达。超声波是频率高于人耳听觉范围的声波，用于扫描或清洗。
Speed of sound in air is about 340 m/s. It travels faster in solids and liquids than in gases because particles are closer together. Light travels much faster, which is why we see lightning before hearing thunder.
声速 在空气中约为 340 m/s。在固体和液体中比在气体中传播更快，因为粒子间距更小。光速快得多，因此我们先看见闪电再听到雷声。
8. Light | 光
Light travels in straight lines called rays. We represent rays with straight arrows. A shadow forms when an opaque object blocks the light's path.
光 沿直线传播，我们用带箭头的直线表示光线。当不透明物体挡住光的路径时，就会形成影子。
Reflection happens when light bounces off a surface. On a smooth mirror, the angle of incidence equals the angle of reflection, measured from the normal. The normal is an imaginary line perpendicular to the surface.
反射 是光从表面弹回的现象。在光滑镜面上，入射角等于反射角，均从法线量起。法线是垂直于表面的假想线。
Refraction is the bending of light when it passes from one medium to another of different density, e.g., air to water. This bending makes a straw in water look broken. Denser medium bends light towards the normal.
折射 是光从一种介质进入密度不同的另一种介质时发生的偏折，例如从空气进入水中。这种偏折让水中的吸管看起来弯折了。光进入更密的介质时向法线偏折。
Lens: a curved piece of glass or plastic that refracts light. A convex lens converges light rays to a focus, forming an image. A concave lens diverges light rays. 'Convex' bulges outward like a cave exit – remember 'convex converges'.
透镜：弯曲的玻璃或塑料片，能使
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