📚 Year 12 SQA Engineering: Vocabulary & Terminology Quick Guide | Year 12 SQA 工程：词汇术语速记指南
Mastering engineering terminology is the foundation of success in Year 12 SQA Engineering Science. This bilingual guide breaks down essential terms from mechanics, materials, electrical systems and control, offering simple definitions and memorable memory hooks to help you recall them quickly during exams and assignments.
掌握工程术语是 Year 12 SQA 工程科学成功的基础。这份双语指南解析了来自力学、材料、电气系统和控制等方面的核心术语，提供简单定义和令人难忘的记忆线索，帮助你在考试和作业中迅速回想。
1. Stress, Strain and Stiffness | 应力、应变与刚度
applied. It is calculated as σ = F / A, where F is the force in newtons and A is the cross‑ a), but engineering values are often in MPa or GPa. A quick memory trick: think of feeling “stressed” – pressure on you from all sides, like force spread over an area.
应力（σ）是材料在承受外部载荷时单位面积上的内力，计算公式为 σ = F / A，其中 F 是牛顿力，A 是横截面积（m²）。单位是帕斯卡（Pa），工程上常用 MPa 或 GPa。快速记忆法：想象自己感到“压力”——就像力分布在你全身的每一块面积上。
nge in length and L₀ is the original length. Since strain has no units, it is often expressed as a percentage. Remember: “strain” – think of a train stretching; strain is the stretch.
应变（ε）是衡量变形的物理量，表示单位原长上的伸长量，无量纲，公式为 ε = ΔL / L₀，ΔL 为长度变化量，L₀ 为原始长度。应变常以百分比表示。记忆提示：“应变”中的“变”指形变，犹如拉伸一段橡皮筋。
. Its unit is pascal (Pa). A high Young’s modulus means the material is very stiff (e.g. steel), while a low value indicates it is flexible (e.g. rubber). Mnemonic: “Young bamboo” is stiff yet bends – just like Young’s modulus measures stiffness.
杨氏模量（E）描述材料的刚度，联系弹性阶段中的应力与应变：E = σ / ε，单位为帕斯卡（Pa）。杨氏模量高表示材料刚性大（如钢），低则柔韧（如橡胶）。记忆诀窍：“Young” 像年轻的竹子一样，硬而有弹性，恰如杨氏模量衡量刚度。
2. Load, Effort and Mechanical Advantage | 负载、作用力与机械效益
Load / Effort. If MA > 1, the machine multiplies the input force, making it easier to lift a heavy load.
在简单机械中，负载是需要克服的阻力，作用力（施力）是为完成工作所施加的力。机械效益 MA = 负载 / 作用力。若 MA > 1，说明机械放大了输入力，让举起重物更省力。
in the same time. VR = distance effort / distance load. Unlike MA, VR is purely geometric – only on the machine’s design, not friction. A pulley system with four ropes has a VR of 4.
速度比（VR）是作用力移动距离与负载移动距离之比，VR = 作用力移动距离 / 负载移动距离。与 MA 不同，VR 仅取决于机械的几何设计，不受摩擦影响。例如，四绳滑轮组的速度比为 4。
how well a machine converts input work into useful output work. It is η = (MA / VR) × 100%. Because of friction and other losses, efficiency is always less than 100%. Memorise: “efficiency is the marriage of MA and VR – the closer they are, the happier the machine.”
效率（η）表示机械将输入功转换为有用输出功的程度，η = (MA / VR) × 100%。由于摩擦等损耗，效率始终低于 100%。记住：“效率就是 MA 和 VR 的婚姻——它们越接近，机器就越幸福。”
3. Moments, Shear and Bending | 力矩、剪切与弯曲
re d is the perpendicular distance from the pivot to the line of action of the force. The unit is newton‑ ). To balance a beam, the sum of clockwise moments equals the sum of anticlockwise moments – the Principle of Moments.
力矩（M）是力绕支点产生的转动效应，M = F × d，d 为支点到力作用线的垂直距离，单位是牛·米（Nm）。要使梁平衡，顺时针力矩之和等于逆时针力矩之和，此即力矩原理。
Shear force at a cross‑section of a beam is the internal force that resists sliding of one part past another. It is caused by transverse loads and is essential for designing beams. Think of scissors: they shear paper apart. Shear force diagrams show how this force varies along the beam.
剪切力是指梁某横截面上阻止两部分相对滑动的内力，由横向载荷引起，是梁设计中不可或缺的考量。联想剪刀剪纸——剪刀把纸“剪”开，正是剪切作用。剪力图展示剪切力沿梁的变化。
Bending moment is the internal moment that causes a beam to bend. It is calculated as the sum of moments on one side of a section. The maximum bending moment often occurs where the shear force is zero. A helpful phrase: “Bending moment makes the beam curve – the bigger the moment, the tighter the bend.”
弯矩是使梁发生弯曲的内力矩，可以通过截面一侧所有力矩之和来计算。最大弯矩常出现在剪力为零的位置。记忆口诀：“弯矩让梁变弯——力矩越大，弯曲越厉害。”
4. Motion, Work and Power | 运动、功和功率
sured in joules (J). Only the component of force in the direction of movement counts. If you push a wall and it does not move, no physical work is done – a useful exam reminder.
功（W）是力推动物体移动一段距离所做的能量转移，W = F × d，单位为焦耳（J）。只有沿移动方向的力分量才做功。推墙但墙不动，则物理做功为零——这是考试中常见的提醒。
P = E / t, and its unit is the watt (W). In electrical terms, P = I × V. To remember, link ‘power’ to ‘powerful engine’: the faster it does work, the more powerful it is.
功率（P）是做功或能量转移的速率，P = W / t 或 P = E / t，单位为瓦特（W）。在电学中 P = I × V。想象一台“强力发动机”——做功越快，功率越大。
on is described by the equations of motion, e.g. v = u + a t and s = u t + ½ a t². Use the mnemonic “SUVAT” for the five quantities: s, u, v, a, t.
速度和速度矢量容易混淆。速率是标量（只有大小），速度是矢量（有大小和方向）。匀加速运动可用运动学方程描述，如 v = u + a t 和 s = u t + ½ a t²。用 “SUVAT” 记忆五个量：位移、初速度、末速度、加速度、时间。
5. Basic Electrical Quantities | 基本电量术语
ate of flow of charge: I = Q / t, measured in amperes (A). Picture current as water flowing through a pipe – the more electrons per second, the higher the current.
电荷（Q）是物质在电磁场中受力的属性，单位是库仑（C）。电流（I）是电荷流动的速率：I = Q / t，单位是安培（A）。把电流想象成水管里流动的水——每秒通过的电子越多，电流越大。
volt (V). It pushes current around a circuit, similar to pressure in a water system. Remember: “Voltage is the push, current is the flow.”
电压（V）或电位差是单位电荷在两点间转移的能量，V = W / Q，单位伏特（V）。电压驱动电荷绕电路流动，类似水系统中的水压。记住：“电压是推力，电流是流动。”
imits current just as a narrow pipe restricts water. Conductance (G = 1/R) is the opposite – the ease with which current can pass.
电阻（R）阻碍电流流动，R = V / I，单位欧姆（Ω）。电阻器限制电流，如同细管限制水流。电导（G = 1/R）则相反，表示电流通过的容易程度。
6. Circuit Laws and Components | 电路定律与元件
uctor at constant temperature. Many problems in SQA Engineering rely on this simple relationship. Memorise the triangle: V at the top, I and R at the bottom – cover the quantity you want to find.
欧姆定律指出，在恒定温度下，对于导体有 V = I × R。SQA 工程中的许多问题都依赖这一简单关系。记忆三角形：V 在上，I 和 R 在下，盖住你想求的量。
Kirchhoff’s Current Law (KCL): the total current entering a junction equals the total current leaving. Kirchhoff’s Voltage Law (KVL): the sum of e.m.f.s around a closed loop equals the sum of p.d.s. Use the phrase “what goes in must come out” for KCL, and “round trip energy balance” for KVL.
基尔霍夫电流定律（KCL）：流入节点的总电流等于流出节点的总电流。基尔霍夫电压定律（KVL）：闭合回路中电动势之和等于电位差之和。用“进多少出多少”记 KCL，用“环路能量守恒”记 KVL。
Key components: a diode allows current in one direction only (think one‑way valve); an LED emits light; a thermistor changes resistance with temperature (negative temperature coefficient); an LDR’s resistance drops when light increases. For transistors, remember “small base current switches large collector current.”
关键元件：二极管只允许单方向电流（类似单向阀）；LED 发光；热敏电阻的阻值随温度变化（负温度系数）；光敏电阻（LDR）光照增强时电阻减小。对于晶体管，记住“小基极电流控制大集电极电流”。
7. Systems and Control Vocabulary | 系统与控制词汇
An open‑loop system has no feedback: output does not affect the input. A closed‑loop system uses feedback to compare the actual output with the desired value and automatically corrects errors. Imagine a toaster (open loop – you set the time) versus a thermostat‑controlled oven (closed loop).
开环系统没有反馈：输出不影响输入。闭环系统利用反馈将实际输出与期望值比较，并自动修正误差。想象烤面包机（开环——你设定时间）与恒温烤箱（闭环）。
A transducer converts one form of energy into another. For example, a microphone converts sound into an electrical signal. An actuator is a device that moves or controls a mechanism, such as a solenoid, motor or hydraulic cylinder.
换能器将一种形式的能量转换为另一种。例如，麦克风将声能转换为电信号。执行器是移动或控制机构的装置，如电磁铁、电机或液压缸。
compressed fluid. Pressure (P) = F / A, and the same principle is used in braking systems. “Force multiplied, speed divided” minder: if you gain force with a hydraulic press, the ram moves slower to conserve energy.
在气动和液压系统中，力通过受压流体传递。压强 P = F / A，制动系统利用相同原理。“力增大，速度减小”是实用的提醒：如果液压机增力，则活塞移动减慢以保持能量守恒。
8. Material Properties and Testing | 材料特性与测试
Elastic limit: the maximum stress a material can withstand and still return to its original shape. Yield point: the stress at which permanent (plastic) deformation begins. Ultimate Tensile Strength (UTS): the maximum stress on the stress‑strain curve. Necking occurs after UTS, leading to fracture.
弹性极限：材料能承受并仍能恢复原状的最大应力。屈服点：开始发生永久（塑性）变形的应力。极限抗拉强度（UTS）：应力‑应变曲线上的最大应力。颈缩现象出现在 UTS 之后，最终导致断裂。
Ductility is the ability to be drawn into a wire (e.g. copper), while brittleness means sudden failure without plastic deformation (e.g. glass). Toughness is the energy absorbed before fracture – think of a tough material that absorbs impact. Hardness resists surface indentation. To recall: “Diamond is hard, rubber is tough, chalk is brittle.”
延展性是拉成线材的能力（如铜），脆性意味着无塑性变形而突然断裂（如玻璃）。韧性是断裂前吸收的能量——想象一种坚韧材料吸收冲击。硬度抵抗表面压痕。记忆：钻石硬，橡胶韧，粉笔脆。
applies within the elastic region, where k is the spring constant. The area under a stress‑ fracture represents the modulus of toughness. A stiff material has a steep elastic slope.
胡克定律（F = k x）适用于弹性阶段，k 为弹簧常数。应力‑应变曲线下直至断裂的面积代表韧性模量。刚性材料的弹性斜率较陡。
9. Energy, Efficiency and Conservation | 能量、效率与守恒
mal, electrical, etc. The principle of conservation of energy states that energy cannot be created or destroyed, only converted. When analysing systems, always account for wasted energy, typically as heat.
能量可分为动能（Eₖ = ½ m v²）、势能（Eₚ = m g h）、热能、电能等。能量守恒定律指出能量不能创生或消灭，只能转换。分析系统时，务必考虑损耗的能量，通常以热的形式散失。
s proportional to energy amounts. The efficiency formula η = (useful output / input) × 100% applies across mechanical, electrical and thermal systems.
工程师使用桑基图显示能量流动，箭头宽度与能量成比例。效率公式 η =（有用输出 / 输入）× 100% 适用于机械、电气和热力系统。
Remember: “You cannot win, you cannot even break even” – a humorous take on thermodynamics, but useful to recall that some energy is always degraded. For SQA problems, list all energy inputs and outputs, then apply conservation and efficiency calculations.
记住：“你赢不了，连平局都达不到”——这是热力学的幽默说法，但有助于记住总有能量被耗散。在 SQA 问题中，列出所有能量输入和输出，然后应用守恒和效率计算。
10. Memory Aids and Common Confusions | 记忆方法与常见误区
The table below clarifies words that often confuse candidates. Learning these distinctions can save you marks in definitions and numerical questions.
下表澄清了考生经常混淆的词汇。学会这些区别能在定义题和计算题中不失分。
| English Term | 中文 | Memory Tip |
|---|---|---|
| Stress vs Strain | 应力 vs 应变 | Stress is 'force/area' (pressure); strain is 'stretch' (extension). |
| Mass vs Weight | 质量 vs 重量 | Mass (kg) is constant; weight (N) depends on gravity (W = mg). |
| Speed vs Velocity | 速率 vs 速度 | Velocity includes direction; speed is just 'how fast'. |
| Moment vs Torque | 力矩 vs 扭矩 | Both are force × distance; torque often relates to twisting shafts. |
| Power vs Energy | 功率 vs 能量 | Power is rate of energy use; energy is capacity to do work. |
| p.d. (voltage) vs e.m.f. | 端电压 vs 电动势 | e.m.f. is the total energy per charge from source; p.d. is across a component. |
Use acronyms and silly sentences to lock formulas in your mind. For example, “Very Important Rabbit” for V=IR; “We Fight Every Monster” for W=F×d (work); “Every Power Ranger Jumps” for E
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