📚 Year 7 AQA Physics: Summer Revision and Bridging Course | Year 7 AQA 物理：暑期预习与衔接课程
Welcome to your summer bridging course for Year 7 AQA Physics. This guide is designed to introduce you to the major topics you will explore throughout the year, from forces and energy to waves, electricity, and the particle model. Each section provides a clear overview of the key ideas and practical skills you need to feel confident as you step from primary science into secondary physics. Take your time, read through the explanations, and try the simple checkpoints along the way.
欢迎来到 Year 7 AQA 物理暑期衔接课。这本指南旨在带你预习这一学年将要探索的主要主题，涵盖力、能量、波、电学以及粒子模型。每一部分都清晰概述了从小学科学过渡到中学物理所需的核心概念和实验技能。请从容阅读，理解解释，并尝试各节中穿插的简单自测问题。
1. Forces – A Push or a Pull | 力——推还是拉？
A force is simply a push or a pull that acts on an object. Forces can change the speed, direction or shape of something. When you kick a football, you apply a force to make it move. The unit of force is the newton (N), named after Sir Isaac Newton. Forces are vector quantities, which means they have both size and direction.
力就是作用在物体上的推或拉。力可以改变物体的速度、方向或形状。当你踢足球时，你施加力使它运动。力的单位是牛顿 (N)，以艾萨克·牛顿爵士命名。力是矢量，这意味着它们既有大小也有方向。
Forces always come in pairs. When you sit on a chair, your weight pushes down on the chair, and the chair pushes back up on you with an equal force. This is called an interaction pair. We often represent forces using arrows in free-body diagrams, where the length of the arrow shows the size of the force and the arrowhead points in the direction it acts.
力总是成对出现的。你坐在椅子上时，你的体重向下压椅子，而椅子用相等的力向上推你。这被称为相互作用力对。我们常用自由体图中的箭头来表示力，箭头的长度表示力的大小，箭头指向力的作用方向。
- Checkpoint: Name three things a force can do to an object. / 自测：说出力对物体产生的三种作用。
2. Contact and Non-contact Forces | 接触力与非接触力
Forces can be grouped into contact forces and non-contact forces. Contact forces, such as friction, air resistance, tension and normal reaction force, only act when objects are physically touching. Non-contact forces, such as gravity, magnetic force and electrostatic force, can act over a distance without direct contact.
力可以分为接触力和非接触力。摩擦力、空气阻力、张力和法向反作用力等接触力仅在物体实际接触时起作用。重力、磁力和静电力等非接触力可以在一定距离上作用而不需要直接接触。
Gravity is a force of attraction between any two masses. On Earth, gravity pulls all objects towards the centre of the planet, giving them weight. Your weight is the gravitational force acting on your mass. The magnetic force can attract or repel magnetic materials, while electrostatic force acts between charged objects.
重力是任意两个质量之间的吸引力。在地球上，重力将所有物体拉向地心，赋予它们重量。你的体重就是作用在你质量上的重力。磁力可以吸引或排斥磁性材料，而静电力作用于带电物体之间。
| Contact Forces | Non-contact Forces |
|---|---|
| Friction | Gravity |
| Air resistance | Magnetic force |
| Tension | Electrostatic force |
| Normal contact force |
3. Balanced Forces and Equilibrium | 平衡力与平衡状态
When the total force acting on an object is zero, we say the forces are balanced. In this situation, a stationary object stays still and a moving object continues moving at a constant speed in a straight line. This is described by Newton’s First Law of Motion.
当作用在物体上的合力为零时，我们说力是平衡的。在这种情况下，静止的物体保持不动，运动的物体以恒定速度沿直线继续运动。这由牛顿第一运动定律描述。
If forces are not balanced, the object will accelerate (speed up), decelerate (slow down) or change direction. The overall force acting on an object is called the resultant force. You find the resultant force by subtracting the smaller force from the larger one when they act in opposite directions, or adding them if they act in the same direction.
如果力不平衡，物体会加速、减速或改变方向。作用在物体上的总力称为合力。当力沿相反方向作用时，用较大的力减去较小的力得出合力；若沿相同方向，则将它们相加。
Resultant force = larger force − smaller force (opposite direction)
- down (10 N) and the table pushing up (10 N). Forces are balanced; resultant force = 0 N. / 例子：桌上的书受到向下的重力 (10 N) 和桌子向上的推力 (10 N)。力平衡，合力为零。
4. Speed and Measuring Motion | 速度与运动测量
Speed tells us how fast something is moving. It is the distance travelled in a certain amount of time. The standard unit for speed in physics is metres per second (m/s), although you will also use miles per hour (mph) in everyday life. You can calculate speed using the equation below.
速度告诉我们物体运动的快慢。它是一定时间内通过的距离。物理学中速度的标准单位是米每秒 (m/s)，但日常生活中也会使用英里每小时 (mph)。你可以用下面的公式计算速度。
speed = distance ÷ time
To measure speed in the lab, you might use a stopwatch to time how long a toy car takes to travel one metre. Distance-time graphs are a useful way of showing an object's motion. A horizontal line means the object is stationary; a straight sloping line means it is moving at a constant speed; the steeper the line, the faster the object.
在实验室测量速度时，你可能会用秒表来计时玩具车通过一米距离所需的时间。距离-时间图是展示物体运动的有用方式。水平线表示物体静止；倾斜直线表示物体匀速运动；线条越陡，物体运动越快。
| Distance (m) | Time (s) | Average speed (m/s) |
| 50 | 10 | 5 |
| 100 | 20 | 5 |
5. Energy Stores and Transfers | 能量储存与转移
Energy is the ability to do work. It cannot be created or destroyed, only transferred from one store to another. This is the principle of conservation of energy. In Year 7 you will learn about energy stores such as kinetic energy (movement), thermal energy (heat), chemical energy (fuels, food), gravitational potential energy (height), elastic potential energy (stretched springs) and nuclear energy.
能量是做功的能力。它不能被创造或毁灭，只能从一个储能转移到另一个。这就是能量守恒定律。在 Year 7，你将学习动能（运动）、热能（热）、化学能（燃料、食物）、重力势能（高度）、弹性势能（拉伸弹簧）和核能等能量储存。
Energy can be transferred mechanically (by a force doing work), by heating, by radiation (light and sound) or electrically. When you turn on a lamp, energy is transferred electrically from the mains to the light bulb, then by radiation as light and by heating as the bulb warms up.
能量可以通过机械方式（力做功）、加热、辐射（光和声）或电的方式进行转移。当你打开一盏灯时，能量通过电的方式从电源转移到灯泡，然后通过辐射以光的形式、通过加热使灯泡变暖的形式转移。
- Quick task: List the energy stores and transfers for a person riding a bicycle up a hill. / 小任务：列出人骑自行车上山时的能量储存和转移。
6. Renewable and Non-renewable Energy Resources | 可再生与不可再生能源
Our electricity and heat come from energy resources. Non-renewable resources, such as coal, oil and natural gas, are fossil fuels that will run out one day. Burning them releases carbon dioxide, which contributes to climate change. Nuclear fuel is also non-renewable but does not produce greenhouse gases during operation.
我们的电力和热能来自能源。煤、石油和天然气等不可再生能源属于化石燃料，终有一天会耗尽。燃烧它们会释放二氧化碳，加剧气候变化。核燃料也是不可再生的，但在运行过程中不产生温室气体。
Renewable resources can be replenished within a human lifetime. These include solar, wind, wave, tidal, hydroelectric, geothermal and biomass. Each has advantages and disadvantages. Solar panels are quiet and produce no pollution once installed, but they only work when the Sun shines. Wind turbines rely on windy weather and some people consider them an eyesore on the landscape.
可再生能源可以在人的一生时间尺度内得到补充。它们包括太阳能、风能、波浪能、潮汐能、水力发电、地热能和生物质能。每种能源各有优缺点。太阳能电池板安装后无噪音、无污染，但仅在阳光照射时工作。风力涡轮机依赖多风天气，且有些人认为它们有碍景观。
A key term you should know is 'carbon neutral'. Wood is considered carbon neutral because the carbon dioxide released when it is burned is roughly equal to the amount absorbed by the tree as it grew. It is important to evaluate energy resources based on reliability, cost, environmental impact and power output.
你需要了解的一个关键术语是'碳中和'。木材被认为碳中和，因为燃烧释放的二氧化碳大致等于树木生长过程中吸收的量。根据可靠性、成本、环境影响和功率输出来评估能源很重要。
7. Sound Waves and How We Hear | 声波与听觉
Sound is a form of energy produced by vibrating objects. These vibrations travel through a medium (solid, liquid or gas) as longitudinal waves. Sound cannot travel through a vacuum because there are no particles to pass on the vibration. In air, sound travels at approximately 330 m/s.
声音是振动物体产生的一种能量形式。这些振动以纵波的形式通过介质（固体、液体或气体）传播。声音不能在真空中传播，因为没有粒子传递振动。在空气中，声速约为 330 m/s。
The loudness of a sound depends on the amplitude of the wave – bigger vibrations produce louder sounds. The pitch (how high or low a note sounds) depends on the frequency – more vibrations per second give a higher pitch. Frequency is measured in hertz (Hz). Humans can typically hear frequencies from 20 Hz to 20 000 Hz.
声音的响度取决于波的振幅——振动越大，声音越响。音调（音符的高低）取决于频率——每秒振动次数越多，音调越高。频率的单位是赫兹 (Hz)。人类通常能听到 20 Hz 到 20 000 Hz 的频率。
The human ear gathers sound waves and funnels them down the ear canal to the eardrum, which vibrates. These vibrations are passed through tiny bones to the cochlea, where they are turned into electrical signals and sent to the brain. Damage to any part of this system can cause hearing loss.
人耳收集声波，沿着耳道传到鼓膜，引起鼓膜振动。这些振动通过小骨传递到耳蜗，在耳蜗内转化为电信号并发送到大脑。该系统的任何部分受损都可能导致听力损失。
8. Light and Reflection | 光与反射
Light is a form of electromagnetic radiation that travels in straight lines at a speed of 300 000 000 m/s in a vacuum. When light hits a smooth, shiny surface like a mirror, it reflects according to the law of reflection: the angle of incidence equals the angle of reflection. These angles are always measured from the normal, an imaginary line at right angles to the surface.
光是一种电磁辐射，在真空中以 300 000 000 m/s 的速度沿直线传播。当光照射到如镜子的光滑、闪亮表面时，它会根据反射定律反射：入射角等于反射角。这些角度总是从法线（垂直于表面的假想线）开始测量。
angle of incidence = angle of reflection
You will draw ray diagrams using a ruler, a sharp pencil and a protractor. The incident ray (incoming light), the reflected ray and the normal all lie in the same plane. We see non-luminous objects because light from a source bounces off them and enters our eyes. Smooth surfaces give a clear reflection (specular), while rough surfaces scatter light in many directions (diffuse reflection).
你将用直尺、尖铅笔和量角器绘制光线图。入射光线、反射光线和法线都位于同一平面内。我们看到不发光的物体，是因为光源发出的光从它们身上反射并进入我们的眼睛。光滑表面产生清晰反射（镜面反射），粗糙表面对光进行多方向散射（漫反射）。
- Try this: If the angle of incidence is 35°, what is the angle of reflection? / 试一试：若入射角为 35°，反射角是多少？
9. Building Simple Electric Circuits | 搭建简单电路
An electric circuit is a closed loop through which electric charge can flow. For a circuit to work, it must be complete and include a source of potential difference (like a battery). Circuit diagrams use standard symbols for components: a cell, battery, bulb, switch, resistor and variable resistor, among others. Drawing neat diagrams with a ruler and labelling components correctly is a key skill.
电路是一个闭合回路，电荷可以从中流过。要使电路工作，它必须是完整的，并包含电动势源（如电池）。电路图使用标准元件符号：电池、灯泡、开关、电阻器和可变电阻器等。用直尺整齐画图并正确标注元件是一项关键技能。
Conductors, such as metals, allow current to flow easily because they have free electrons. Insulators, such as plastic and rubber, do not conduct electricity and are used to coat wires for safety. The current is a measure of the flow of charge, measured in amperes (A). Voltage (potential difference) is the energy transferred per unit of charge, measured in volts (V).
导体（如金属）因为有自由电子而允许电流轻松流过。绝缘体（如塑料和橡胶）不导电，用于包裹电线以保证安全。电流是电荷流动的量度，单位为安培 (A)。电压（电势差）是每单位电荷转移的能量，单位为伏特 (V)。
| Component | Symbol (description) |
|---|---|
| Cell | Long line (+) and short line (−) |
| Battery | Two or more cells joined |
| Lamp | Circle with a cross inside |
| Switch (open) | Break in the line with a small gap |
10. Current and Voltage in Series Circuits | 串联电路中的电流与电压
In a series circuit, components are connected one after another in a single loop. There is only one path for the current to flow. The current is the same at every point in a series circuit. This means if you place an ammeter anywhere in the loop, it will read the same value. If one component breaks, the whole circuit stops working – that is why fairy lights wired in series all go out when one bulb blows.
在串联电路中，元件一个接一个地连接在单一回路中。电流只有一条路径可走。串联电路中各点的电流相同。这意味着将电流表放在回路中的任何位置，读数都一样。如果一个元件损坏，整个电路停止工作——这就是为何串联的节日彩灯只要一只坏掉就全部熄灭。
Voltage, however, is shared between components in series. The total voltage supplied by the battery equals the sum of the voltages across each component. You can investigate this using a voltmeter connected in parallel across each bulb. In Year 8 you will compare this with parallel circuits where components are on separate branches and current splits.
然而，串联电路中的电压由各个元件分担。电池提供的总电压等于各个元件两端电压之和。你可以通过将电压表并联在每个灯泡两端来探究这一点。在 Year 8，你会将此与并联电路进行比较，并联电路中元件位于不同支路且电流分流。
Vtotal = V₁ + V₂ + V₃ ...
- Practical tip: Always connect the ammeter in series and the voltmeter in parallel. / 实验提示：电流表总是串联连接，电压表总是并联连接。
11. The Particle Model and States of Matter | 粒子模型与物态
The particle model explains the behaviour of solids, liquids and gases. All substances are made up of tiny particles that are constantly moving. In a solid, particles are held closely together in a fixed, regular arrangement and can only vibrate in place. In a liquid, particles are close together but can move past each other, so liquids flow and take the shape of their container. In a gas, particles are far apart and move rapidly in all directions, filling any available space.
粒子模型解释了固体、液体和气体的行为。所有物质都由不断运动的微小粒子组成。在固体中，粒子紧密固定、规则排列，只能在原处振动。在液体中，粒子距离近但可以相互滑动，因此液体会流动并呈现容器的形状。在气体中，粒子相距很远且快速向各个方向运动，充满任何可用空间。
| State | Particle arrangement | Particle movement |
|---|---|---|
| Solid | Regular, fixed positions | Vibrate around a point |
| Liquid | Random, close together | Move past each other |
| Gas | Random, far apart | Fast in all directions |
The particle model also explains why solids have a fixed shape and volume, liquids have a fixed volume but no fixed shape, and gases have neither. Adding energy (heating) makes particles move faster, while cooling slows them down. This links directly to changes of state.
粒子模型也解释了为什么固体有固定形状和体积，液体有固定体积但无固定形状，气体两者都没有。增加能量（加热）使粒子运动加快，而冷却则使其减慢。这直接与物态变化相关。
12. Changes of State and Conservation of Mass | 物态变化与质量守恒
Changes of state are physical changes, not chemical reactions, so no new substances are made. The main changes are melting (solid to liquid), freezing (liquid to solid), boiling/evaporation (liquid to gas), condensation (gas to liquid), sublimation (solid to gas) and deposition (gas to solid). During a change of state, the temperature remains constant even though energy is still being transferred. This is because the energy is used to break bonds between particles rather than raise temperature.
物态变化是物理变化，而非化学反应，因此不会产生新物质。主要的变化包括熔化（固→液）、凝固（液→固）、沸腾/蒸发（液→气）、冷凝（气→液）、升华（固→气）和凝华（气→固）。在物态变化过程中，尽管能量仍在传递，温度却保持不变。这是因为能量用于打破粒子间的键，而不是升高温度。
A key principle is the conservation of mass: when a substance changes state, the total mass stays the same because the number of particles does not change. You can investigate this by melting an ice cube in a sealed bag and finding the mass before and after. Diffusion is evidence for the particle model: a smell spreading across a room happens because gas particles move randomly and mix.
一个关键原理是质量守恒：当物质改变状态时，总质量保持不变，因为粒子的数量没有变化。你可以通过在密封袋中融化冰块并测量前后质量来探究这一点。扩散是粒子模型的证据：气味在房间中弥漫是因为气体粒子随机运动并混合。
- Key vocabulary: Melting point (temperature at which solid turns to liquid), boiling point (temperature at which liquid turns to gas throughout). / 核心词汇：熔点（固体变为液体的温度），沸点（液体内部变为气体的温度）。
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