Year 7 WJEC Physics: Formula & Theorem Quick Reference Handbook | Year 7 WJEC 物理：公式定理速查手册

📚 Year 7 WJEC Physics: Formula & Theorem Quick Reference Handbook | Year 7 WJEC 物理：公式定理速查手册

This quick reference guide brings together the most important equations and principles you will encounter in Year 7 WJEC Physics. Mastering these formulas will help you solve problems on speed, forces, energy, electricity, and more.

本速查指南汇集了 Year 7 WJEC 物理中你会遇到的最重要的方程和原理。掌握这些公式将帮助你解决有关速度、力、能量、电学等方面的题目。

1. Speed Calculation | 速度计算

Speed tells you how fast an object is moving. It is calculated by dividing the distance travelled by the time taken.

速度告诉你物体运动的快慢。它通过将行驶的距离除以所用的时间来计算。

v = d ÷ t

Where v is the speed (in metres per second, m/s), d is the distance (in metres, m) and t is the time (in seconds, s).

其中 v 是速度（单位：米每秒，m/s），d 是距离（单位：米，m），t 是时间（单位：秒，s）。

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2. Acceleration | 加速度

Acceleration measures how quickly an object changes its velocity. It is the change in velocity divided by the time taken for that change.

加速度衡量物体速度变化的快慢。它是速度变化量除以发生该变化所用的时间。

a = Δv ÷ t

Here, a is acceleration (m/s²), Δv is the change in velocity (m/s) and t is the time (s). The symbol Δ (delta) means 'change in'.

这里，a 是加速度（单位：m/s²），Δv 是速度变化量（单位：m/s），t 是时间（单位：s）。符号 Δ（delta）表示“变化量”。

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3. Newton's Second Law | 牛顿第二定律

Newton's Second Law relates the force applied to an object, its mass, and the resulting acceleration. A bigger force gives a bigger acceleration, but a larger mass gives a smaller acceleration for the same force.

牛顿第二定律将作用在物体上的力、其质量和产生的加速度联系起来。力越大，加速度越大；但对于相同的力，质量越大，加速度越小。

F = m × a

F is the force in newtons (N), m is the mass in kilograms (kg) and a is the acceleration in metres per second squared (m/s²).

F 是力（单位：牛顿，N），m 是质量（单位：千克，kg），a 是加速度（单位：米每二次方秒，m/s²）。

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4. Weight and Mass | 重量与质量

Weight is the force of gravity acting on an object. It depends on the mass of the object and the gravitational field strength (g). On Earth, g is approximately 10 N/kg (or 9.8 N/kg).

重量是作用在物体上的重力。它取决于物体的质量和重力场强度（g）。在地球上，g 大约是 10 牛/千克（或 9.8 牛/千克）。

W = m × g

W is the weight in newtons (N), m is the mass in kilograms (kg) and g is the gravitational field strength in newtons per kilogram (N/kg).

W 是重量（单位：牛顿，N），m 是质量（单位：千克，kg），g 是重力场强度（单位：牛/千克，N/kg）。

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5. Work Done | 做功

Work is done when a force moves an object through a distance. Energy is transferred when work is done.

当力使物体移动一段距离时，就做了功。做功时能量被转移。

W = F × d

W is the work done in joules (J), F is the force in newtons (N) and d is the distance moved in the direction of the force in metres (m).

W 是做功（单位：焦耳，J），F 是力（单位：牛顿，N），d 是沿力的方向移动的距离（单位：米，m）。

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6. Kinetic Energy | 动能

Kinetic energy is the energy an object has because of its motion. It depends on the object's mass and the square of its speed.

动能是物体因运动而具有的能量。它取决于物体的质量和速度的平方。

KE = ½; × m × v²

KE is the kinetic energy in joules (J), m is the mass in kilograms (kg) and v is the speed in metres per second (m/s).

KE 是动能（单位：焦耳，J），m 是质量（单位：千克，kg），v 是速度（单位：米/秒，m/s）。

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7. Gravitational Potential Energy | 重力势能

Gravitational potential energy (GPE) is the energy stored in an object because of its height above the ground. The higher the object, the greater the GPE.

重力势能（GPE）是物体由于离地面有一定高度而储存的能量。物体越高，重力势能越大。

GPE = m × g × h

GPE is the gravitational potential energy in joules (J), m is the mass in kg, g is the gravitational field strength (N/kg) and h is the height in metres (m).

GPE 是重力势能（单位：焦耳，J），m 是质量（单位：kg），g 是重力场强度（单位：N/kg），h 是高度（单位：米，m）。

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8. Power | 功率

Power is the rate at which work is done or energy is transferred. A more powerful appliance transfers more energy each second.

功率是做功或能量转移的速率。功率越大的电器，每秒钟转移的能量越多。

P = W ÷ t or P = E ÷ t

P is the power in watts (W), W is the work done in joules (J), E is the energy transferred in joules (J) and t is the time in seconds (s).

P 是功率（单位：瓦特，W），W 是做功（单位：焦耳，J），E 是转移的能量（单位：焦耳，J），t 是时间（单位：秒，s）。

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9. Density | 密度

Density describes how much mass is packed into a given volume. Dense materials have a lot of mass in a small volume.

密度描述单位体积内所含质量的多少。致密材料在较小的体积内含有很大的质量。

ρ = m ÷ V

ρ (rho) is the density in kilograms per cubic metre (kg/m³), m is the mass in kilograms (kg) and V is the volume in cubic metres (m³).

ρ（rho）是密度（单位：千克每立方米，kg/m³），m 是质量（单位：千克，kg），V 是体积（单位：立方米，m³）。

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10. Pressure | 压强

Pressure is the force exerted per unit area. A sharp knife has a small area, so it exerts high pressure and cuts easily.

压强是单位面积上所受的力。锋利的刀面积很小，因此产生高压，容易切割。

p = F ÷ A

p is the pressure in pascals (Pa), F is the force in newtons (N) and A is the area in square metres (m²).

p 是压强（单位：帕斯卡，Pa），F 是力（单位：牛顿，N），A 是面积（单位：平方米，m²）。

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11. Ohm's Law | 欧姆定律

Ohm's Law describes the relationship between voltage, current and resistance in an electrical circuit. It allows you to calculate one quantity if the other two are known.

欧姆定律描述了电路中电压、电流和电阻之间的关系。如果知道其中两个量，就可以计算第三个量。

R = V ÷ I

R is the resistance in ohms (Ω), V is the voltage in volts (V) and I is the current in amperes (A).

R 是电阻（单位：欧姆，Ω），V 是电压（单位：伏特，V），I 是电流（单位：安培，A）。

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12. Wave Equation | 波动方程

The wave equation links the speed of a wave to its frequency and wavelength. All waves obey this equation.

波动方程将波速与频率和波长联系起来。所有波都遵守这个方程。

v = f × λ

v is the wave speed in metres per second (m/s), f is the frequency in hertz (Hz) and λ (lambda) is the wavelength in metres (m).

v 是波速（单位：米/秒，m/s），f 是频率（单位：赫兹，Hz），λ（lambda）是波长（单位：米，m）。

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Published by TutorHao | Physics Revision Series | aleveler.com

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