📚 Year 7 Edexcel Physics: Quick Reference Formula and Theorem Handbook | 7年级 Edexcel 物理：公式定理速查手册
This handbook provides a concise summary of all key formulas and theorems covered in Year 7 Edexcel Physics. It is designed as a quick revision aid, with each section pairing essential concepts in simple English and Chinese for bilingual learners. Memorise the symbols, units and relationships to build a strong foundation for later physics study.
本手册简明地汇总了 7 年级 Edexcel 物理课程中的关键公式和定理，旨在为双语学习者提供快速复习辅助。每个小节都将核心概念用简洁的英文和中文配对呈现。熟记这些符号、单位和关系，为今后的物理学习打好坚实基础。
1. Speed, Distance and Time | 速度、距离和时间
Speed describes how quickly an object moves. The relationship between speed, distance and time is one of the most fundamental equations in physics: speed equals the distance travelled divided by the time taken. If you know any two of the three quantities, you can calculate the third.
速度描述物体运动的快慢。速度、距离和时间之间的关系是物理学最基本的方程之一：速度等于走过的距离除以所用的时间。如果你知道三个量中的任意两个，就可以计算出第三个。
v = s / t or speed = distance ÷ time
Where: v = speed (m/s), s = distance (m), t = time (s). Rearranged forms are distance = speed × time and time = distance ÷ speed. Always ensure the units are consistent – convert km to m before calculations if needed.
其中：v = 速度（米/秒），s = 距离（米），t = 时间（秒）。变形式为：距离 = 速度 × 时间，时间 = 距离 ÷ 速度。务必确保单位一致——如有需要，计算前将千米转换为米。
2. Acceleration | 加速度
Acceleration measures the rate at which velocity changes. An object accelerates if it speeds up, slows down (deceleration) or changes direction. The formula links change in velocity and the time taken for that change.
加速度衡量速度变化的快慢。物体加快、减慢（减速度）或改变方向时都有加速度。公式将速度的变化量与发生该变化所用时间联系起来。
a = (v – u) / t
Where: a = acceleration (m/s²), v = final velocity (m/s), u = initial velocity (m/s), t = time (s). Acceleration can be positive (speeding up) or negative (slowing down). In many Year 7 problems, objects start from rest so u = 0.
其中：a = 加速度（米/秒²），v = 末速度（米/秒），u = 初速度（米/秒），t = 时间（秒）。加速度可以为正（加速）或负（减速）。在许多 7 年级的题目中，物体从静止开始，因此 u = 0。
3. Density, Mass and Volume | 密度、质量和体积
Density tells you how much mass is packed into a certain volume. Substances with high density feel heavy for their size. The formula is widely used to identify materials and explain floating and sinking.
密度表示单位体积内所含质量的多少。密度高的物质，同样体积下更重。这一公式广泛用于辨别材料以及解释沉浮现象。
ρ = m / V or density = mass ÷ volume
Where: ρ (Greek letter rho) = density (kg/m³ or g/cm³), m = mass (kg or g), V = volume (m³ or cm³). For irregular solids, volume can be found by water displacement. Always use matching units – for example, if mass is in grams, volume should be in cm³.
其中：ρ（希腊字母 rho）= 密度（千克/米³ 或 克/厘米³），m = 质量（千克或克），V = 体积（米³ 或 厘米³）。对于不规则固体，可用排水法测量体积。务必使用匹配的单位——例如，若质量用克，体积就应用立方厘米。
4. Pressure, Force and Area | 压强、力和面积
Pressure is a measure of how concentrated a force is on a surface. A small area gives high pressure, which is why sharp objects cut easily. The pressure formula explains everyday phenomena from snowshoes to hydraulic systems.
压强衡量力作用在表面上的集中程度。面积小则压强大，这就是锋利物体容易切割的原因。压强公式可解释从雪鞋到液压系统的日常现象。
P = F / A or pressure = force ÷ area
Where: P = pressure (N/m² or Pascal, Pa), F = force (N), A = area (m²). Note that 1 Pa = 1 N/m². To reduce pressure, increase the area over which the force acts – this is why lorries carrying heavy loads have wide tyres.
其中：P = 压强（牛/米² 或帕斯卡 Pa），F = 力（牛），A = 面积（米²）。注意 1 Pa = 1 N/m²。要减小压强，可以增大力的作用面积——这就是重载卡车使用宽轮胎的原因。
5. Forces and Newton’s Second Law | 力与牛顿第二定律
Forces cause changes in motion. Newton’s Second Law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This relationship is often summarised by the well‑known formula.
力导致运动状态改变。牛顿第二定律指出，物体的加速度与作用在其上的合外力成正比，与物体的质量成反比。这个关系常被概括为著名的公式。
F = m × a or force = mass × acceleration
Where: F = force (N), m = mass (kg), a = acceleration (m/s²). This means a larger force produces a larger acceleration, and a more massive object requires a greater force to achieve the same acceleration. Remember to consider only the resultant (net) force.
其中：F = 力（牛），m = 质量（千克），a = 加速度（米/秒²）。这意味着力越大加速度越大，而质量越大的物体要达到同样的加速度则需要更大的力。记住，只考虑合力（净力）。
6. Work Done | 做功
In physics, work is done when a force moves an object in the direction of the force. Energy is transferred when work is done. The amount of work can be calculated by multiplying the force by the distance moved in the direction of the force.
在物理学中，当力使物体沿力的方向移动时，就说力做了功。做功时能量发生转移。功的大小可通过力乘以沿力方向移动的距离来计算。
W = F × d or work done = force × distance
Where: W = work done (J, joules), F = force (N), d = distance moved (m). If the force and motion are perpendicular, no work is done. The unit joule is defined as the work done when a force of 1 N moves an object 1 m.
其中：W = 功（焦耳 J），F = 力（牛），d = 移动的距离（米）。如果力与运动方向垂直，则不做功。焦耳这个单位的定义就是当 1 牛的力使物体移动 1 米时所做的功。
7. Gravitational Potential Energy | 重力势能
Any object lifted against gravity stores energy called gravitational potential energy (GPE). The higher the object and the greater its mass, the more GPE it possesses. This energy can be converted into kinetic energy if the object falls.
任何被举高反抗重力的物体都储存了能量，称为重力势能 (GPE)。物体位置越高、质量越大，其重力势能就越多。如果物体下落，这种能量会转化为动能。
GPE = m × g × h
Where: m = mass (kg), g = gravitational field strength (on Earth ≈ 10 N/kg or 9.8 N/kg), h = height above a reference point (m). The unit is joule (J). In calculations, always use the value of g given in the question.
其中：m = 质量（千克），g = 重力场强度（地球上约 10 N/kg 或 9.8 N/kg），h = 相对于参考点的高度（米）。单位是焦耳 (J)。计算时，请务必使用题目给出的 g 值。
8. Kinetic Energy | 动能
Kinetic energy is the energy of a moving object. Every moving object has kinetic energy, and the amount depends on mass and speed. The formula shows that speed has a much greater effect than mass because it is squared.
动能是运动物体具有的能量。任何运动的物体都有动能，其大小取决于质量和速度。公式表明，速度对动能的影响远比质量大，因为速度带平方项。
KE = ½ × m × v²
Where: KE = kinetic energy (J), m = mass (kg), v = speed (m/s). Doubling the speed quadruples the kinetic energy. This is why high‑speed collisions are far more damaging. Always remember to square the speed before multiplying.
其中：KE = 动能（焦耳），m = 质量（千克），v = 速度（米/秒）。速度加倍，动能增为原来的四倍。这就是高速碰撞破坏性巨大的原因。计算时务必先求速度的平方再乘以其他量。
9. Moments | 力矩
A moment is the turning effect of a force around a pivot. It depends on both the size of the force and the perpendicular distance from the pivot to the line of action of the force. Moments explain how levers work and why long spanners are easier to use.
力矩是力绕支点产生的转动效果。它既取决于力的大小，也取决于从支点到力作用线的垂直距离。力矩原理能解释杠杆如何工作，以及为什么长扳手用起来更省力。
M = F × d
Where: M = moment (Nm, newton‑metre), F = force (N), d = perpendicular distance from the pivot (m). For an object in rotational equilibrium, the sum of clockwise moments equals the sum of anticlockwise moments – this is the principle of moments.
其中：M = 力矩（牛·米），F = 力（牛），d = 从支点到力线的垂直距离（米）。对于处于转动平衡的物体，顺时针力矩之和等于逆时针力矩之和——这就是力矩平衡原理。
10. Electrical Quantities and Ohm’s Law | 电学量与欧姆定律
In electric circuits, voltage drives current through a conductor, while resistance opposes the flow. Ohm’s Law states that the current through a resistor at constant temperature is directly proportional to the voltage across it and inversely proportional to its resistance.
在电路中，电压驱动电流通过导体，而电阻则阻碍电流流动。欧姆定律指出，在温度恒定下，通过电阻的电流与它两端的电压成正比，与电阻成反比。
V = I × R
Where: V = voltage (V), I = current (A), R = resistance (Ω, ohms). This can be rearranged to I = V / R and R = V / I. A component that obeys this linear relationship is called an ohmic conductor. Remember that resistance changes with temperature for many materials.
其中：V = 电压（伏特），I = 电流（安培），R = 电阻（欧姆）。可变形为 I = V / R 和 R = V / I。遵循这一线性关系的元件称为欧姆导体。请注意，许多材料的电阻会随温度变化。
11. Electrical Power | 电功率
Power is the rate at which energy is transferred or work is done. In electrical circuits, the power delivered to a component depends on the voltage across it and the current flowing through it. Knowing power helps you choose suitable fuses and cables.
功率是能量传递或做功的速率。在电路中，输送到元器件的功率取决于其两端的电压和流过它的电流。了解功率有助于选择合适的保险丝和导线。
P = V × I or power = voltage × current
Where: P = power (W, watts), V = voltage (V), I = current (A). This formula can be combined with Ohm’s Law to give P = I²R or P = V² / R. The watt is equivalent to one joule per second. Appliances with higher power ratings transfer more energy each second.
其中：P = 功率（瓦特 W），V = 电压（伏特），I = 电流（安培）。该公式与欧姆定律结合可得 P = I²R 或 P = V² / R。1 瓦特等于 1 焦耳每秒。额定功率越高的电器每秒转化的能量越多。
12. Energy Transfers and Conservation | 能量转移与守恒定律
Energy can be stored in different forms – kinetic, gravitational potential, thermal, chemical, elastic, nuclear, and more. The principle of conservation of energy states that energy cannot be created or destroyed, only transferred from one store to another or between objects.
能量可以以不同形式储存——动能、重力势能、热能、化学能、弹性势能、核能等。能量守恒定律指出，能量既不会凭空产生也不会凭空消失，它只能从一种储存形式转移到另一种，或在物体之间传递。
When a ball is dropped, gravitational potential energy is transferred to kinetic energy. In a stretched rubber band, elastic potential energy is stored. Sankey diagrams can show energy transfers, with the width of the arrows representing the amount of energy. Understanding energy efficiency helps design machines that waste less energy as heat.
当球下落时，重力势能转化为动能。被拉伸的橡皮筋中储存着弹性势能。桑基图可以展示能量转移过程，箭头的宽度代表能量的大小。理解能量效率有助于设计出浪费热更少的机器。
Efficiency = useful output energy / total input energy
Efficiency is often expressed as a percentage. No real machine is 100% efficient because some energy is always transferred to thermal energy due to friction and resistance.
效率通常以百分数表示。现实中没有任何机器能达到 100% 的效率，因为摩擦和电阻总会使一部分能量转化为热能。
Published by TutorHao | Physics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导