📚 Year 8 SQA Physics: Formula & Theorem Quick Reference | SQA 物理公式定理速查手册
This quick reference handbook provides a concise summary of the key formulas, laws, and principles you need to master for the Year 8 SQA Physics course. It is designed to help you revise efficiently, understand the relationships between physical quantities, and apply them correctly in exam questions. Each section includes the essential formula, its variable definitions, units, and a brief explanation of the underlying theorem or concept.
本速查手册为你总结了 Year 8 SQA 物理课程必须掌握的核心公式、定律和原理。它能帮助你高效复习，理解物理量之间的关系，并在考试题目中正确应用。每个小节都包含了基本公式、变量定义、单位以及对相关定理或概念的简要说明。
1. Speed, Distance and Time | 速度、距离与时间
Speed is a measure of how fast an object is moving. It is defined as the distance travelled per unit of time. The average speed can be calculated when the total distance and total time are known.
速度是衡量物体运动快慢的物理量，定义为单位时间内通过的距离。当已知总距离和总时间时，可以计算平均速度。
v = d ÷ t
In this equation, v represents speed (in metres per second, m/s), d represents distance (in metres, m), and t represents time (in seconds, s). Remember that if the distance is given in kilometres and time in hours, the speed will be in kilometres per hour (km/h).
在这个公式中，v 代表速度（单位米每秒，m/s），d 代表距离（单位米，m），t 代表时间（单位秒，s）。请记住，如果距离以千米为单位，时间以小时为单位，那么速度的单位就是千米每小时（km/h）。
2. Acceleration | 加速度
Acceleration is the rate at which an object's velocity changes over time. It is a vector quantity, meaning it has both magnitude and direction. Deceleration (negative acceleration) occurs when an object slows down.
加速度是物体速度随时间变化的快慢，是一个具有大小和方向的矢量。当物体减速时，会出现负加速度（即减速度）。
a = (v – u) ÷ t
Where a is acceleration (m/s²), v is final velocity (m/s), u is initial velocity (m/s), and t is the time taken (s). The change in velocity (v – u) is sometimes written as Δv. The unit m/s² means 'metres per second per second', indicating how much the velocity changes every second.
其中 a 是加速度（m/s²），v 是末速度（m/s），u 是初速度（m/s），t 是所用时间（s）。速度的变化量 (v – u) 有时也写作 Δv。单位 m/s² 表示“米每二次方秒”，意为每秒速度变化的量。
3. Newton's Second Law of Motion | 牛顿第二运动定律
This fundamental law describes the relationship between the force applied to an object, its mass, and the acceleration it experiences. It states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
这一定律描述了施加在物体上的力、物体的质量及其加速度之间的关系。它指出，物体的加速度与作用在其上的净外力成正比，与物体的质量成反比。
F = m × a
F is the resultant (net) force measured in newtons (N), m is the mass in kilograms (kg), and a is the acceleration in metres per second squared (m/s²). One newton is defined as the force needed to accelerate a 1 kg mass by 1 m/s².
F 是合力（净力），单位为牛顿（N）；m 是质量，单位为千克（kg）；a 是加速度，单位为米每二次方秒（m/s²）。一牛顿的定义是使 1 kg 的物体产生 1 m/s² 加速度所需的力。
4. Weight and Mass | 重量与质量
Weight is the force of gravity acting on an object's mass. Unlike mass, which is a measure of the amount of matter and is constant everywhere, weight depends on the gravitational field strength and can change if you go to another planet.
重量是作用在物体质量上的重力。与质量（衡量物质多少的量，处处相同）不同，重量取决于引力场强度，如果去到其他星球上会发生变化。
W = m × g
Here W is weight in newtons (N), m is mass in kilograms (kg), and g is the gravitational field strength. On Earth, g is approximately 9.8 N/kg (often rounded to 10 N/kg in SQA problems). This formula shows that weight is directly proportional to mass.
式中 W 是重量，单位为牛顿（N）；m 是质量，单位为千克（kg）；g 是引力场强度。在地球上，g 约为 9.8 N/kg（SQA 题目中常取 10 N/kg）。该公式表明重量与质量成正比。
5. Pressure | 压强
Pressure is a measure of how concentrated a force is over a given area. It explains why a sharp knife cuts more easily than a blunt one – the same force applied over a smaller area produces greater pressure.
压强衡量的是力在给定面积上的集中程度。这解释了为什么锋利的刀比钝刀更容易切割——相同的力施加在更小的面积上会产生更大的压强。
P = F ÷ A
P stands for pressure in pascals (Pa), F is the force applied at right angles to the surface in newtons (N), and A is the area over which the force is spread in square metres (m²). 1 Pa is equal to 1 N/m².
P 代表压强，单位为帕斯卡（Pa）；F 是垂直于表面的力，单位为牛顿（N）；A 是力作用的面积，单位为平方米（m²）。1 Pa 等于 1 N/m²。
6. Work Done and Energy | 功与能量
In physics, 'work done' is the amount of energy transferred when a force moves an object. Work and energy are both measured in joules (J). When work is done, energy is converted from one form to another.
在物理学中，“做功” 是指力使物体发生位移时所转移的能量。功和能量的单位都是焦耳（J）。当做功时，能量从一种形式转化为另一种形式。
W = F × d
W is the work done in joules (J), F is the constant force applied in the direction of motion in newtons (N), and d is the distance moved by the object in metres (m). Note that if the force is not parallel to the displacement, only the component of the force in the direction of motion does work.
W 是做的功，单位为焦耳（J）；F 是沿运动方向施加的恒力，单位为牛顿（N）；d 是物体移动的距离，单位为米（m）。注意，如果力不平行于位移，只有沿运动方向的分力做功。
7. Power | 功率
Power is the rate at which work is done or energy is transferred. A more powerful machine does the same amount of work in less time, or more work in the same time.
功率是做功或能量转移的速率。一台功率更大的机器能在更短的时间内做同样的功，或在相同的时间内做更多的功。
P = W ÷ t
P is power in watts (W), W is the work done
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