📚 Year 7 Edexcel Physics: Core Knowledge Organiser | Year 7 Edexcel 物理核心知识点梳理
Welcome to the ultimate revision guide for Year 7 Edexcel Physics. This article brings together all the essential concepts you need to master, from forces and energy to waves and electricity. Each section is carefully structured with clear explanations and real-world links to help you build confidence and succeed in your assessments.
欢迎阅读 Year 7 Edexcel 物理终极复习指南。本文汇集了你需要掌握的所有核心概念，从力、能量到波和电学。每个部分都经过精心编排，提供清晰的解释和与现实生活的联系，帮助你建立信心，在测评中取得成功。
1. What is a Force? | 什么是力？
A force is a push or a pull acting on an object. Forces are measured in newtons (N) and can be contact forces, like friction and tension, or non-contact forces, such as gravity, magnetism and electrostatic attraction.
力是作用在物体上的推或拉。力的单位是牛顿（N），可以是接触力，如摩擦力和张力，也可以是非接触力，如重力、磁力和静电引力。
Forces can change the speed, direction or shape of an object. For instance, kicking a ball changes its motion, while stretching a spring changes its shape.
力可以改变物体的速度、方向或形状。例如，踢足球会改变它的运动状态，拉伸弹簧则会改变它的形状。
We represent forces using arrows in diagrams. The length of the arrow shows the magnitude (size) of the force, and the arrowhead points in the direction the force acts.
我们在示意图中用箭头表示力。箭头的长度表示力的大小，箭头指向力的作用方向。
2. Balanced and Unbalanced Forces | 平衡力与非平衡力
When forces on an object are balanced, the resultant force is zero. The object will either stay still or continue moving at a constant speed in a straight line.
当作用在物体上的力平衡时，合力为零。物体将保持静止或沿直线匀速运动。
If forces are unbalanced, there is a resultant force. This causes the object to accelerate, decelerate or change direction. A book sliding off a table speeds up downwards because of unbalanced weight.
如果力不平衡，就会产生合力。这会使得物体加速、减速或改变方向。一本书从桌面滑落时会因为不平衡的重力而向下加速。
Free body diagrams help us visualise all forces acting on one object, such as weight, normal reaction, friction and thrust.
受力图帮助我们直观看出作用在一个物体上的所有力，比如重力、支持力、摩擦力和推力。
3. Speed and Distance-Time Graphs | 速度与距离-时间图
Speed tells us how quickly an object moves. We calculate it using the equation:
速度告诉我们物体运动的快慢，可使用以下公式计算：
speed = distance ÷ time
Common units are metres per second (m/s) and kilometres per hour (km/h). If a car travels 100 metres in 5 seconds, its average speed is 20 m/s.
常用单位是米每秒（m/s）和千米每小时（km/h）。如果一辆汽车在5秒内行驶了100米，它的平均速度就是20 m/s。
A distance-time graph shows how distance changes over a period. A horizontal line means the object is stationary. A straight sloping line means constant speed. The steeper the slope, the greater the speed.
距离-时间图显示距离随时间的变化情况。水平线表示物体静止，倾斜的直线表示匀速运动。斜率越大，速度越快。
Curved lines on the graph indicate acceleration or deceleration, because the speed is changing.
图中的曲线表示加速或减速，因为速度在发生变化。
4. Energy Stores and Transfers | 能量储存与转移
Energy is measured in joules (J) and exists in different stores: kinetic (movement), gravitational potential (height), elastic potential (stretched or compressed), thermal (heat), chemical (food, fuel) and nuclear.
能量以焦耳（J）为单位，储存在不同的形式中：动能（运动）、重力势能（高度）、弹性势能（拉伸或压缩）、热能（温度）、化学能（食物、燃料）和核能。
Energy can be transferred from one store to another by four main pathways: mechanically (by a force doing work), electrically (by a current), by heating or by radiation (light and sound).
能量可以通过四种主要途径从一个储存库转移到另一个：机械做功（力做功）、电做功（电流）、加热或辐射（光和声）。
For example, when you drop a ball, gravitational potential energy is transferred to kinetic energy mechanically. When a bulb lights, chemical energy in the battery is transferred electrically to light and thermal energy.
例如，当你扔下一个球时，重力势能通过机械做功转化为动能。当灯泡亮起时，电池中的化学能通过电做功转化为光和热能。
5. Conservation of Energy and Resources | 能量守恒与能源
The law of conservation of energy states that energy cannot be created or destroyed, only transferred or converted from one form to another. The total energy before and after any change remains constant.
能量守恒定律指出，能量不能被创造或毁灭，只能从一种形式转移或转化为另一种形式。任何变化前后的总能量保持不变。
We rely on energy resources to generate electricity. Renewable resources include solar, wind, wave, tidal and hydroelectric power. Non-renewable resources include coal, oil and natural gas, which are finite and produce carbon dioxide when burned.
我们依靠能源来发电。可再生能源包括太阳能、风能、波浪能、潮汐能和水力发电。不可再生能源包括煤、石油和天然气，这些资源有限且燃烧时会产生二氧化碳。
Using renewable resources helps reduce environmental impact, but some depend on weather conditions and can be less reliable than fossil fuels.
使用可再生能源有助于减少对环境的影响，但有些能源依赖天气条件，可能比化石燃料的可靠性低。
6. The Particle Model | 粒子模型
All matter is made up of tiny particles that are constantly moving. The arrangement and motion of these particles determine whether a substance is a solid, liquid or gas.
所有物质都由不断运动的微小粒子组成。这些粒子的排列和运动方式决定了物质是固体、液体还是气体。
In solids, particles are tightly packed in a regular pattern and vibrate in fixed positions. In liquids, particles are close together but can slide past each other. In gases, particles are widely spaced and move rapidly in all directions.
固体中，粒子紧密排列成规则的结构，在固定位置上振动。液体中，粒子彼此靠近但能相互滑动。气体中，粒子间距很大，快速向各个方向运动。
Diffusion is the spreading out of particles from an area of high concentration to low concentration. It happens faster in gases than in liquids because gas particles move more freely.
扩散是粒子从高浓度区域向低浓度区域散布的过程。气体中的扩散比液体中更快，因为气体粒子运动更自由。
7. States of Matter and Changes of State | 物态与物态变化
Matter can change state when energy is added or removed. Melting (solid to liquid) and boiling (liquid to gas) require energy input. Freezing (liquid to solid) and condensation (gas to liquid) release energy.
当加入或移除能量时，物质会发生状态变化。熔化（固态变液态）和沸腾（液态变气态）需要吸收能量。凝固（液态变固态）和凝结（气态变液态）则释放能量。
Evaporation occurs at the surface of a liquid at any temperature, while boiling happens throughout the liquid at a specific boiling point.
蒸发可以在任何温度下液体表面发生，而沸腾是在特定沸点整个液体内部发生的剧烈汽化。
During a change of state, the temperature stays constant even though energy is still being transferred. This energy is used to break intermolecular bonds rather than to raise the temperature.
在物态变化过程中，尽管能量仍在转移，温度却保持不变。这些能量用于破坏粒子间的结合，而不是提高温度。
Sublimation is the direct change from solid to gas, like dry ice turning into carbon dioxide gas, skipping the liquid phase.
升华是指固体直接变成气体的过程，例如干冰变成二氧化碳气体，跳过了液态阶段。
8. Electric Circuits | 电路
An electric circuit is a closed loop that allows current to flow from the positive terminal to the negative terminal of a power supply. Basic components include cells, batteries, lamps, switches and buzzers.
电路是一个闭合回路，允许电流从电源的正极流向负极。基本元件包括电池、电池组、灯泡、开关和蜂鸣器。
We use standard circuit symbols to draw circuits clearly. A cell is shown with a long line (+) and a short line (−). Switches, lamps and ammeters each have their own recognised symbol.
我们使用标准电路符号来清晰地绘制电路。电池用一长一短的线条表示（+和−）。开关、灯泡和电流表都有各自公认的符号。
In a series circuit, components are connected in a single loop. If one component fails, the circuit is broken and all components stop working. In a parallel circuit, there are multiple branches, so components can operate independently.
在串联电路中，各元件连接在一条回路中。如果一个元件发生故障，电路断开，所有元件都停止工作。在并联电路中，存在多条支路，因此各元件可以独立工作。
9. Current, Voltage and Resistance | 电流、电压与电阻
Electric current is the flow of charge. It is measured in amperes (A) using an ammeter connected in series. The greater the current, the more charge flows each second.
电流是电荷的流动，用电流表串联在电路中测量，单位是安培（A）。电流越大，每秒通过的电量越多。
Voltage (potential difference) is the energy transferred per unit charge, measured in volts (V) with a voltmeter connected in parallel. It pushes the current around the circuit.
电压（电势差）是每单位电荷转移的能量，用电压表并联测量，单位是伏特（V）。电压推动电流在电路中流动。
Resistance is a measure of how difficult it is for current to flow, measured in ohms (Ω). A higher resistance reduces the current for a given voltage.
电阻是衡量电流流动难易程度的物理量，单位是欧姆（Ω）。在电压一定时，电阻越大，电流越小。
In series circuits, the current is the same everywhere, but the supply voltage is shared between components. In parallel circuits, the voltage across each branch is the same as the supply, while the current splits at junctions.
串联电路中，各处电流相等，但电源电压会分配给各元件。并联电路中，各支路电压与电源电压相同，而电流会在分支点分流。
10. Sound Waves | 声波
Sound is produced by vibrating objects and travels as longitudinal waves through a medium such as air, liquid or solid. It cannot travel through a vacuum because there are no particles to vibrate.
声音由振动产生，并以纵波的形式通过空气、液体或固体等介质传播。声音不能在真空中传播，因为没有粒子可以振动。
The amplitude of a sound wave determines its loudness. A wave with greater amplitude carries more energy and sounds louder. Frequency determines pitch; a higher frequency means a higher-pitched sound.
声波的振幅决定其响度。振幅越大，携带的能量越多，听起来越响。频率决定音调；频率越高，音调越高。
The human ear detects sound waves. The outer ear collects sound, the eardrum vibrates, and tiny bones in the middle ear transmit these vibrations to the cochlea, where they are converted into electrical signals for the brain.
人耳检测声波。外耳收集声音，鼓膜振动，中耳的小骨将这些振动传递给耳蜗，在耳蜗中转化为电信号传至大脑。
Ultrasound is sound with a frequency above 20 000 Hz, beyond human hearing. It is used in medical imaging and sonar.
超声波是指频率高于20 000 Hz、超出人耳听觉范围的声音，常用于医学成像和声呐。
11. Light, Reflection and Refraction | 光、反射与折射
Light travels in straight lines as transverse waves and does not need a medium, so it can travel through a vacuum at about 300 000 000 m/s.
光以横波形式沿直线传播，不需要介质，因此能在真空中以约300 000 000 m/s的速度传播。
When light hits a smooth surface, it obeys the law of reflection: the angle of incidence equals the angle of reflection. Both angles are measured from the normal, a line perpendicular to the surface.
光照射到光滑表面时，遵循反射定律：入射角等于反射角。这两个角都是从法线（垂直于表面的线）开始测量的。
Refraction occurs when light passes from one transparent medium to another and changes speed, causing it to bend. For example, a pencil in a glass of water appears bent at the surface due to refraction.
折射发生在光从一种透明介质进入另一种介质并改变速度时，导致光线弯曲。例如，水杯中的铅笔由于折射在水面处看起来是弯的。
White light can be split into a spectrum of colours (red, orange, yellow, green, blue, indigo, violet) through a prism. This is called dispersion and happens because different colours refract by different amounts.
白光可以通过棱镜分解成七色光谱（红、橙、黄、绿、蓝、靛、紫），这称为色散，因为不同颜色的光折射程度不同。
12. The Solar System and Beyond | 太阳系与更远的世界
Our solar system consists of the Sun, eight planets and many moons, dwarf planets, asteroids and comets. The Sun, a star, is at the centre and provides the gravitational pull that keeps the planets in orbit.
我们的太阳系由太阳、八大行星和众多卫星、矮行星、小行星和彗星组成。太阳这颗恒星位于中心，它提供的引力使行星保持在轨道上运行。
The inner planets (Mercury, Venus, Earth, Mars) are rocky, while the outer planets (Jupiter, Saturn, Uranus, Neptune) are gas giants. Moons orbit planets, and artificial satellites orbit Earth for communication and research.
内行星（水星、金星、地球、火星）由岩石构成，外行星（木星、土星、天王星、海王星）是气态巨行星。卫星围绕行星运行，人造卫星围绕地球运行，用于通信和研究。
The Earth rotates on its axis once every 24 hours, causing day and night. It orbits the Sun once every 365.25 days, and the tilt of its axis leads to the seasons.
地球每24小时绕地轴自转一周，形成昼夜。地球每365.25天绕太阳公转一周，地轴的倾斜导致了四季变化。
Gravity is the non-contact force that attracts all objects with mass. The strength of gravity on Earth gives things weight and keeps our atmosphere in place.
引力是一种非接触力，它吸引所有具有质量的物体。地球的引力使物体具有重量，并把大气层维持在周围。
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