📚 Year 7 AQA Science: Quick Reference Formula & Theorem Handbook | Year 7 AQA 科学：公式定理速查手册
Welcome to your essential quick-reference handbook for Year 7 AQA Science. This guide collects the key formulas, equations and scientific principles you will meet in physics, chemistry and biology. Use it to revise topics, practise calculations and build confidence in how science explains everyday phenomena.
欢迎使用你的 Year 7 AQA 科学必备速查手册。本指南汇集了你在物理、化学和生物课程中会遇到的关键公式、方程式和科学原理。用它来复习专题、练习计算，并增强对科学如何解释日常现象的理解。
1. Speed Formula | 速度公式
Speed describes how fast an object moves. It is a measure of the distance travelled in a certain amount of time.
速度描述物体运动的快慢。它衡量的是在一定时间内通过的距离。
speed = distance ÷ time
In symbols: v = d ÷ t.
用符号表示：v = d ÷ t。
mula triangle to rearrange the equation: distance = speed × time, time = distance ÷ speed.
常用单位是米每秒（m/s）和千米每小时（km/h）。你可以使用公式三角形来转换方程：距离 = 速度 × 时间，时间 = 距离 ÷ 速度。
Example: A cyclist travels 150 metres in 30 seconds. Their speed is 150 ÷ 30 = 5 m/s.
示例：一名自行车手在30秒内行驶了150米。他的速度是 150 ÷ 30 = 5 m/s。
2. Density Formula | 密度公式
Density tells you how much mass is packed into a certain volume. It helps to identify materials and predict whether they will float or sink.
密度告诉你一定体积内聚集了多少质量。它帮助识别材料并预测它们会浮起还是下沉。
density = mass ÷ volume
In symbols: ρ = m ÷ V. Units are grams per cubic centimetre (g/cm³) or kilograms per cubic metre (kg/m³).
用符号表示：ρ = m ÷ V。单位是克每立方厘米（g/cm³）或千克每立方米（kg/m³）。
Water has a density of about 1 g/cm³. Objects with density less than 1 g/cm³ float; those with greater density sink.
水的密度大约为1 g/cm³。密度小于1 g/cm³的物体会浮起；密度更大的则会下沉。
etal has mass 200 g and volume 50 cm³. Density = 200 ÷ 50 = 4 g/cm³, so it sinks in water.
示例：一块金属的质量为200克，体积为50立方厘米。密度 = 200 ÷ 50 = 4 g/cm³，因此它在水中下沉。
3. Weight, Mass and Gravity | 重量、质量与重力
Mass is the amount of matter in an object, measured in kilograms (kg). Weight is the force of gravity pulling on that mass, measured in newtons (N).
质量是物体所含物质的多少，用千克（kg）衡量。重量是重力对质量的拉力，用牛顿（N）衡量。
weight = mass × gravitational field strength
W = m × g
On Earth, the gravitational field strength (g) is about 10 N/kg. Your weight changes if you go to the Moon because g is smaller, but your mass stays the same.
在地球上，引力场强度（g）约为10 N/kg。如果你去月球，重量会改变，因为g更小，但你的质量保持不变。
Example: A student has a mass of 45 kg. Weight on Earth = 45 × 10 = 450 N.
示例：一名学生质量为45千克。在地球上的重量 = 45 × 10 = 450 N。
4. Pressure Formula | 压强公式
Pressure tells you how concentrated a force is over an area. A small area gives a large pressure, while a large area gives a small pressure.
压强表示力在面积上的集中程度。面积越小，压强越大；面积越大，压强越小。
pressure = force ÷ area
P = F ÷ A
Units are newtons per square metre (N/m²), also called pascals (Pa). Sharp objects like pins easily push into surfaces because they concentrate force onto a tiny area.
单位是牛顿每平方米（N/m²），也称为帕斯卡（Pa）。像大头针这样的尖锐物体很容易扎入表面，因为它们把力集中在一个极小的面积上。
Example: A force of 300 N acts on an area of 2 m². Pressure = 300 ÷ 2 = 150 N/m².
示例：300 N的力作用在2 m²的面积上。压强 = 300 ÷ 2 = 150 N/m²。
5. Hooke’s Law | 胡克定律
When you stretch a spring, it extends. Hooke’s Law says the extension is directly proportional to the force applied, as long as you do not exceed its elastic limit.
当你拉伸弹簧时，它会伸长。胡克定律指出，只要不超过弹性限度，伸长量与施加的力成正比。
force = spring constant × extension
F = k × e
The spring constant (k) tells you how stiff the spring is. A stiffer spring has a larger k value.
弹簧常数（k）表示弹簧的刚度。越硬的弹簧k值越大。
xtends by 0.04 m when a force of 10 N is applied. Spring constant k = 10 ÷ 0.04 = 250 N/m.
示例：施加10 N的力时，弹簧伸长0.04 m。弹簧常数k = 10 ÷ 0.04 = 250 N/m。
6. Energy Efficiency | 能量效率
Whenever energy is transferred, some of it is usually wasted as heat or sound. Efficiency tells you how much of the input energy is converted into useful output.
每当能量转移时，部分通常会以热能或声能形式浪费掉。效率告诉你输入能量中有多少转化为有用的输出。
efficiency = (useful output energy ÷ total input energy) × 100%
Sankey diagrams help visualise energy transfers, showing useful energy and wasted energy as arrows.
桑基图帮助可视化能量传递，将有用能量和浪费能量用箭头表示。
0 J of electrical energy and gives out 15 J of light energy. Efficiency = (15 ÷ 100) × 100% = 15%.
示例：一盏灯接收100 J电能，发出15 J光能。效率 = (15 ÷ 100) × 100% = 15%。
7. Law of Reflection | 反射定律
When light bounces off a smooth surface such as a mirror, it follows a simple rule: the angle of incidence equals the angle of reflection.
当光从镜子等光滑表面反射时，它遵循一条简单规则：入射角等于反射角。
angle of incidence = angle of reflection
Both angles are measured from the imaginary normal line – a line drawn at 90° to the surface at the point where the light ray hits. The incident ray, reflected ray and normal all lie in the same plane.
两个角度都是从虚构的法线——在光线照射点处垂直于表面画的一条线——测量得到的。入射光线、反射光线和法线都在同一平面内。
Example: If a light ray strikes a mirror at 30° to the normal, it reflects away at 30° to the normal.
示例：如果一条光线以与法线成30°的角度射向镜子，它将以与法线成30°的角度反射出去。
8. Chemical Word Equations | 化学文字方程式
In Year 7 you learn to write word equations to describe chemical reactions. No numbers or symbols are needed – just the names of reactants and products.
在7年级你将学习书写描述化学反应的文字方程式。不需要数字或符号——只需反应物和生成物的名称。
acid + alkali → salt + water
utralisation. For example, hydrochloric acid + sodium hydroxide → sodium chloride + water.
这是中和反应。例如，盐酸 + 氢氧化钠 → 氯化钠 + 水。
metal + acid → salt + hydrogen
ochloric acid → magnesium chloride + hydrogen. The squeaky pop test confirms hydrogen gas.
示例：镁 + 盐酸 → 氯化镁 + 氢气。爆鸣试验可确认氢气。
metal + oxygen → metal oxide
For instance, iron + oxygen → iron oxide. This is an oxidation reaction.
例如，铁 + 氧气 → 氧化铁。这是一种氧化反应。
9. Photosynthesis Equation | 光合作用方程式
Plants make their own food using sunlight, carbon dioxide and water. This process takes place in chloroplasts and releases oxygen as a by-product.
植物利用阳光、二氧化碳和水制造自己的食物。这一过程发生在叶绿体中，并释放氧气作为副产品。
carbon dioxide + water → glucose + oxygen
Light energy and chlorophyll are needed for the reaction to occur, but they are not written as reactants or products. Glucose is used for energy and growth, while oxygen is released into the air.
反应的发生需要光能和叶绿素，但它们并不作为反应物或生成物写出。葡萄糖用于能量和生长，氧气则被释放到空气中。
The word equation summarises a process that is vital for life on Earth, providing both food and oxygen.
这个文字方程式概括了对地球生命至关重要的过程，它同时提供了食物和氧气。
10. Aerobic Respiration Equation | 有氧呼吸方程式
All living cells release energy through respiration. Aerobic respiration uses oxygen to break down glucose, producing carbon dioxide, water and energy.
所有活细胞通过呼吸作用释放能量。有氧呼吸利用氧气分解葡萄糖，产生二氧化碳、水和能量。
glucose + oxygen → carbon dioxide + water (+ energy)
Energy is released, but it is not a chemical substance, so it is often written in brackets. This reaction happens in the mitochondria of cells and supplies energy for muscle contraction, growth and staying warm.
能量虽然被释放，但它不是化学物质，因此常写在括号中。该反应发生在细胞的线粒体中，为肌肉收缩、生长和保持体温提供能量。
Remember that breathing is not the same as respiration – breathing moves air in and out of the lungs, while respiration is the chemical process inside cells.
请记住，呼吸并不是呼吸作用——呼吸是将气体吸入和呼出肺部，而呼吸作用是细胞内的化学过程。
Published by TutorHao | Science Revision Series | aleveler.com
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