Year 8 CIE Physics: Formula & Theorem Quick Reference Handbook | Year 8 CIE 物理：公式定理速查手册

📚 Year 8 CIE Physics: Formula & Theorem Quick Reference Handbook | Year 8 CIE 物理：公式定理速查手册

This quick reference handbook covers all essential formulas and theorems in the Year 8 CIE Physics curriculum. It is designed to help you revise key concepts and solve numerical problems efficiently. Keep it handy for tests and homework.

本速查手册涵盖 Year 8 CIE 物理课程中所有重要公式和定理，旨在帮助你高效复习核心概念并解决计算问题。请随身携带，方便测验和作业使用。

1. Units and Measurement | 单位与测量

The International System of Units (SI) provides a standard set of base units for physical quantities. The most common base units are: length in metres (m), mass in kilograms (kg), time in seconds (s), electric current in amperes (A), and temperature in kelvins (K). In Year 8 physics, you will also use degrees Celsius (°C) for temperature, where 0 °C = 273 K.

国际单位制 (SI) 为物理量提供了一套标准基本单位。最常用的基本单位有：长度——米 (m)，质量——千克 (kg)，时间——秒 (s)，电流——安培 (A)，温度——开尔文 (K)。在 Year 8 物理中，你也会使用摄氏度 (°C) 表示温度，其中 0 °C = 273 K。

Common prefixes are used to express very large or very small quantities: kilo (k) = 10³, centi (c) = 10⁻², milli (m) = 10⁻³, and micro (μ) = 10⁻⁶. For example, 1 kilometre = 1000 metres, and 1 milliampere = 0.001 amperes.

常用前缀用于表示极大或极小的量：千 (k) = 10³，厘 (c) = 10⁻²，毫 (m) = 10⁻³，微 (μ) = 10⁻⁶。例如，1 千米 = 1000 米，1 毫安 = 0.001 安。

2. Speed and Motion | 速度与运动

Average speed is the total distance travelled divided by the total time taken. It tells you how fast an object is moving overall, even if the speed changes during the journey.

平均速度等于总路程除以总时间。它告诉你物体在整个运动过程中的快慢程度，即使途中速度有变化。

v = d / t

速度 = 距离 ÷ 时间，v = d / t，其中 v 是速度，d 是距离，t 是时间。速度的标准单位是米每秒 (m/s)。

On a distance–time graph, a straight sloping line represents constant speed. The steeper the slope (gradient), the higher the speed. A horizontal line shows the object is stationary.

在距离—时间图中，一条倾斜的直线表示匀速运动。斜率越大，速度越快。水平线表示物体静止。

3. Forces and Weight | 力与重量

Weight is the force of gravity acting on an object. It depends on the object’s mass and the strength of the gravitational field. Weight is different from mass: mass measures the amount of matter (kg), while weight is a force (N).

重量是重力作用在物体上的力。它取决于物体的质量和引力场的强度。重量与质量不同：质量是物体所含物质的多少（kg），而重量是一种力（N）。

W = m × g

重量 = 质量 × 引力场强度，W = m × g，其中 W 是重量 (N)，m 是质量 (kg)，g 是引力场强度。在地球表面，g ≈ 10 N/kg。

Hooke’s Law states that the extension of a spring is directly proportional to the force applied, as long as the elastic limit is not exceeded. This means doubling the force doubles the extension.

胡克定律指出：只要不超过弹性限度，弹簧的伸长量与施加的力成正比。这意味着力增大一倍，伸长量也增大一倍。

4. Density | 密度

Density explains how much mass is packed into a given volume. Objects with high density sink in low-density fluids if the object’s density is greater than the fluid’s density.

密度表示单位体积内包含的质量。高密度物体会在密度较低的液体中下沉，前提是物体的密度大于液体的密度。

ρ = m / V

密度 = 质量 ÷ 体积，ρ = m / V，其中 ρ 是密度，m 是质量，V 是体积。常用单位有千克每立方米 (kg/m³) 和克每立方厘米 (g/cm³)。

You can find the density of an irregular solid by measuring its mass on a balance and its volume using a displacement can and measuring cylinder. Then apply the formula.

测量不规则固体的密度时，先用天平测质量，再用量筒和溢水杯测体积，然后代入公式计算。

5. Pressure | 压强

Pressure measures how concentrated a force is over a surface. A large force applied over a small area produces high pressure, while the same force over a large area gives low pressure.

压强表示力在表面上的集中程度。同样的力作用在较小的面积上产生高压强，作用在较大的面积上则产生低压强。

更多咨询请联系16621398022（同微信）