KS3 Cambridge Science: Formula & Theorem Quick-Reference Handbook | KS3 Cambridge 科学：公式定理速查手册

📚 KS3 Cambridge Science: Formula & Theorem Quick-Reference Handbook | KS3 Cambridge 科学：公式定理速查手册

This quick-reference handbook compiles the most important formulas, laws and relationships from the KS3 Cambridge Science curriculum. It covers physics, chemistry and biology essentials in an easy‑to‑scan bilingual format, perfect for revision and exam preparation.

本速查手册汇总了 KS3 剑桥科学课程中最重要的公式、定律和数量关系，涵盖物理、化学和生物核心内容，采用中英双语对照，方便复习与备考。

1. Motion and Forces | 运动与力

Average speed = total distance ÷ total time (v = d / t)
Speed describes how fast an object covers a distance. The SI unit is metre per second (m/s). If the speed changes, we talk about average speed.

平均速度 = 总距离 ÷ 总时间。速度表示物体运动快慢，国际单位是米每秒（m/s）。速度变化时，常取平均速度。

Acceleration = change in velocity ÷ time taken (a = (v – u) / t)
Acceleration is how quickly the velocity of an object changes. u is the initial velocity, v is the final velocity. The unit is m/s². A negative acceleration means deceleration.

加速度 = 速度变化量 ÷ 时间。u 为初速度，v 为末速度，单位是 m/s²。负加速度表示减速。

Weight = mass × gravitational field strength (W = m g)
Weight is the force on an object due to gravity. On Earth, g ≈ 9.8 N/kg (often rounded to 10 N/kg). Weight is measured in newtons (N) and is not the same as mass.

重量 = 质量 × 重力场强度。地球上 g≈9.8 N/kg（常取 10 N/kg）。重量是力，单位牛顿，与质量不同。

Resultant force = mass × acceleration (F = m a) – Newton’s Second Law
If a resultant (unbalanced) force acts on an object, it will accelerate. Greater force gives larger acceleration, while greater mass gives smaller acceleration for the same force.

合力 = 质量 × 加速度（牛顿第二定律）。合力不为零时物体必产生加速度；力越大加速度越大，质量越大则同样力产生的加速度越小。

Hooke’s Law: extension is proportional to force (F = k x)
For a spring within its elastic limit, the extension (x) is directly proportional to the applied force (F). k is the spring constant, measured in N/m.

胡克定律：在弹性限度内，弹簧的伸长量 x 与施加的力 F 成正比。k 为劲度系数，单位 N/m。

Pressure = force ÷ area (P = F / A)
Pressure is the amount of force applied over a given area. The SI unit is the pascal (Pa), where 1 Pa = 1 N/m². Large area reduces pressure (e.g. snowshoes).

压强 = 压力 ÷ 面积。单位帕斯卡（Pa），1 Pa=1 N/m²。面积越大压强越小（如雪鞋）。

Moment of a force = force × perpendicular distance from pivot (M = F d)
The turning effect of a force is called the moment. It is measured in newton metres (N m). To increase the moment, apply a larger force or increase the distance from the pivot.

力矩 = 力 × 力臂（力到支点的垂直距离）。单位是牛·米（N m）。增大力或力臂都可增大力矩。

2. Energy, Work and Power | 能量、功与功率

Work done = force × distance moved in the direction of the force (W = F d)
Work is done when a force causes displacement. The energy transferred equals the work done and is measured in joules (J).

做功 = 力 × 沿力方向移动的距离。做功引起能量转移，单位焦耳（J）。

Gravitational potential energy (GPE) = mass × g × height (Eₚ = m g h)
GPE is the energy stored in an object because of its height above the ground. The higher the object, the greater its GPE.

重力势能 = 质量 × 重力场强度 × 高度。物体离地面越高，重力势能越大。

Kinetic energy = ½ × mass × (speed)² (Eₖ = ½ m v²)
Moving objects possess kinetic energy. Doubling the speed quadruples the kinetic energy.

动能 = ½ × 质量 × 速度²。速度加倍时动能增至四倍。

Power = work done ÷ time taken (P = W / t)
Power is the rate at which work is done or energy is transferred. The unit is the watt (W); 1 W = 1 J/s.

功率 = 做功 ÷ 时间。功率是做功或能量转移的速率，单位瓦特（W），1 W=1 J/s。

Efficiency = (useful output energy ÷ total input energy) × 100%
Efficiency tells us how much of the input energy is converted into useful work. No machine is 100% efficient due to energy dissipation (often as heat).

效率 = (有用输出能量 ÷ 总输入能量) × 100%。总有能量耗散（如热能），效率不可能达到 100%。

3. Electricity | 电学

Ohm’s Law: voltage = current × resistance (V = I R)
Voltage (potential difference) is measured in volts (V), current in amperes (A), and resistance in ohms (Ω). This law holds for ohmic conductors at constant temperature.

欧姆定律：电压 = 电流 × 电阻。电压单位伏特（V），电流安培（A），电阻欧姆（Ω）。适用于温度恒定的欧姆导体。

Resistors in series: Rₜ = R₁ + R₂ + R₃ + …
When resistors are connected end‑to‑end, the total resistance increases because the current has to pass through each resistor in turn.

串联电阻：总电阻 Rₜ =R₁+R₂+…。电流依次经过各个电阻，总电阻增大。

Resistors in parallel: 1/Rₜ = 1/R₁ +

Published by TutorHao | KS3 Science Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）