📚 Year 11 SQA Engineering: Quick Reference Handbook of Formulas and Theorems | SQA 工程(Year 11):公式定理速查手册
This comprehensive quick reference handbook compiles all the essential formulas and theorems required for the Year 11 SQA Engineering Science course. It covers mechanics, electricity, electronics, energy and materials, and for every relationship it gives the symbol, the unit, the physical meaning and a short worked example. Used properly, this handbook is not a list to memorise blindly but a revision map: read a section, close the page, and try to rebuild the formula and its units from memory.
这本综合速查手册汇编了 SQA 工程科学(Year 11)课程所需的全部基本公式与定理,涵盖力学、电学、电子学、能量与材料。每一条关系式都给出符号、单位、物理含义和一个简短例题。使用得当时,它不是一份需要死记硬背的清单,而是一张复习地图:读完一节,合上页面,试着凭记忆把公式和单位重新推导出来。
Every formula below is written with Unicode symbols so that it displays correctly on any device. Where a derivation is required by the course, the derivation is explained in words rather than quoted as a result, because SQA marking schemes reward correct method, correct substitution and correct units far more than a memorised final answer.
下文所有公式均使用 Unicode 符号书写,确保在任何设备上都能正确显示。凡课程要求推导的内容,本书都用文字说明推理过程,而不是直接给出结论,因为 SQA 评分标准奖励的是正确方法、正确代入与正确单位,而不是背下来的最终答案。
1. SI Units, Prefixes and Dimensional Consistency | 国际单位、词头与量纲一致性
In engineering, a numerical answer without a unit is meaningless. SQA markers award method marks for correct substitution, so the safest habit is to convert every quantity into SI base or derived units before you substitute it into an equation.
在工程中,没有单位的数值答案毫无意义。SQA 阅卷会为正确的代入给出方法分,因此最稳妥的习惯是:在代入方程之前,先把每个量换算成 SI 基本单位或导出单位。
| Quantity 物理量 | Base unit 基本单位 | Symbol 符号 |
|---|---|---|
| Length 长度 | metre 米 | m |
| Mass 质量 | kilogram 千克 | kg |
| Time 时间 | second 秒 | s |
| Electric current 电流 | ampere 安培 | A |
| Temperature 温度 | kelvin 开尔文 | K |
The common prefixes you must recognise instantly are tera (T, 10¹²), giga (G, 10⁹), mega (M, 10⁶), kilo (k, 10³), centi (c, 10⁻²), milli (m, 10⁻³), micro (µ, 10⁻⁶) and nano (n, 10⁻⁹). A millimetre is therefore 10⁻³ m and a megawatt is 10⁶ W.
必须一眼认出的常见词头包括:tera(T,10¹²)、giga(G,10⁹)、mega(M,10⁶)、kilo(k,10³)、centi(c,10⁻²)、milli(m,10⁻³)、micro(µ,10⁻⁶)、nano(n,10⁻⁹)。因此 1 毫米 = 10⁻³ m,1 兆瓦 = 10⁶ W。
- Force 力: 1 N = 1 kg·m·s⁻²
1 牛顿 = 1 千克·米·秒⁻² - Energy 能量: 1 J = 1 N·m = 1 kg·m²·s⁻²
1 焦耳 = 1 牛·米 - Power 功率: 1 W = 1 J·s⁻¹
1 瓦特 = 1 焦耳每秒 - Pressure and stress 压强与应力: 1 Pa = 1 N·m⁻²
1 帕斯卡 = 1 牛每平方米 - Charge 电荷量: 1 C = 1 A·s
1 库仑 = 1 安培·秒 - Potential difference 电压: 1 V = 1 J·C⁻¹ = 1 W·A⁻¹
1 伏特 = 1 焦耳每库仑 - Resistance 电阻: 1 Ω = 1 V·A⁻¹
1 欧姆 = 1 伏特每安培
f speed. If your rearrangement produces m·s, you have inverted the fraction and lost the mark.
量纲检验是发现变形错误最快的方法。以平均速度 v = d / t 为例:单位是 m ÷ s = m·s⁻¹,正是速度的单位。如果你变形后得到 m·s,说明分数写反了,分数就丢了。
2. Linear Motion and the Equations of Motion | 直线运动与运动方程
Uniformly accelerated motion is the backbone of the mechanics unit. The five equations below are linked, and any problem can be solved by choosing the equation that contains the three known quantities and the single unknown quantity.
匀加速直线运动是力学板块的骨架。下面五个方程彼此关联,解题关键是选出那个"包含三个已知量与一个未知量"的方程。
| Quantity 物理量 | Formula 公式 | Units 单位 |
|---|---|---|
| Average speed 平均速度 | v = d / t | m·s⁻¹ |
| Acceleration 加速度 | a = (v − u) / t | m·s⁻² |
| Final velocity 末速度 | v = u + at | m·s⁻¹ |
| Displacement 位移 | s = ut + ½at² | m |
| Velocity squared 速度平方关系 | v² = u² + 2as | m²·s⁻² |
| Average velocity form 平均速度式 | s = ½(u + v)t | m |
v = u + at s = ut + ½at² v² = u² + 2as
ation and the area under the line is the displacement. Free fall is simply accelerated motion with u = 0 and a = g = 9.8 m·s⁻² downwards.
运动图像的分值不亚于公式本身。距离-时间图上的斜率是速度;速度-时间图上的斜率是加速度,线下的面积是位移。自由落体不过是 u = 0、a = g = 9.8 m·s⁻²(向下)的匀加速运动。
Worked example 例题: ⁻¹ in 6.0 s. Then a = (20 − 8) / 6.0 = 2.0 m·s⁻², and s = ½(u + v)t = ½ × 28 × 6.0 = 84 m.
例题:一辆汽车在 6.0 s 内由 8 m·s⁻¹ 加速到 20 m·s⁻¹。则 a = (20 − 8) / 6.0 = 2.0 m·s⁻²,s = ½(u + v)t = ½ × 28 × 6.0 = 84 m。
3. Forces, Newton's Laws, Moments and Momentum | 力、牛顿定律、力矩与动量
Force is a vector: it has magnitude, direction and a point of application. Newton' ; the third law states that action and reaction are equal, opposite and act on different bodies.
力是矢量:有大小、方向和作用点。牛顿第一定律指出,若合力为零,物体保持静止或匀速直线运动;第二定律给出合力 F = ma;第三定律指出作用力与反作用力大小相等、方向相反,且作用在不同物体上。
- Weight 重力: W = mg, with g = 9.8 N·kg⁻¹ on Earth
W = mg,地球上 g = 9.8 N·kg⁻¹ - Resultant force 合力: F = ma
F = ma - Moment of a force 力矩: M = Fd, where d is the perpendicular distance from the pivot
M = Fd,d 为力到支点的垂直距离 - Principle of moments 力矩平衡原理: Σ clockwise moments = Σ anticlockwise moments
Σ 顺时针力矩 = Σ 逆时针力矩 - Equilibrium 平衡条件: ΣF = 0 and ΣM = 0
ΣF = 0 且 ΣM = 0 - Pressure 压强: P = F / A
P = F / A - Momentum 动量: p = mv
p = mv - Impulse 冲量: Ft = Δp = mv − mu
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