📚 Year 11 SQA Engineering: Core Concepts Overview | SQA 工程课程（11 年级）核心知识点梳理
This article provides a structured overview of the key topics covered in the Year 11 SQA Engineering Science course (typically National 5). It is designed to help you consolidate your understanding of engineering principles, from systems analysis to materials and electronics. Each section presents core concepts in bite-sized English-Chinese pairs to support bilingual learners and reinforce essential knowledge for exams.
本文系统梳理了 SQA 工程科学（11 年级，相当于 National 5）的核心知识点，旨在帮助你将工程原理、系统分析、材料与电子等关键概念融会贯通。每个小节采用中英双语配对要点，便于双语学习者巩固基础，高效备战考试。
1. Engineering Systems and Subsystems | 工程系统与子系统
Every engineered product can be viewed as a system with a clear input, process, and output. The boundary of the system separates it from the surroundings, and a subsystem is a smaller system within the overall system.
任何工程产品都可以视作一个系统，包含明确的输入、处理与输出环节。系统边界将系统与周围环境隔开，子系统则是整体系统内部的一个较小系统。
Open-loop systems have no feedback, so output does not influence the input. Closed-loop systems use feedback to compare actual output with desired output and make automatic adjustments.
开环系统没有反馈，输出不会影响输入。闭环系统则利用反馈将实际输出与期望输出进行比较，并自动进行调整。
Block diagrams are used to represent systems, with arrows showing the flow of energy, material, or information. Typical blocks include input sensor, controller, actuator, and output.
方框图用于表示系统，箭头标示能量、物料或信息的流动。常见的模块包括输入传感器、控制器、执行器和输出部分。
2. Forces and Motion | 力与运动
Scalars have magnitude only (e.g., speed, mass, energy), while vectors have both magnitude and direction (e.g., velocity, force, acceleration). Free-body diagrams are used to represent all forces acting on an object.
标量仅有大小（如速率、质量、能量），矢量则同时具有大小和方向（如速度、力、加速度）。受力分析图用于标示作用在物体上的所有力。
Newton' cceleration. Friction always opposes motion and can be reduced by lubrication or using smoother surfaces.
牛顿第二定律指出合外力 F = m × a，其中 m 为质量，a 为加速度。摩擦力总是阻碍运动，可通过润滑或使用更光滑表面来减小。
with g = 9.8 N/kg. In equilibrium, the vector sum of all forces acting on a body is zero.
地球上的重力即为重量 W = m × g，g = 9.8 N/kg。当物体处于平衡状态时，所有作用力的矢量和为零。
3. Energy, Work, and Power | 能量、功与功率
s and d is distance moved in the direction of the force. Energy is the capacity to do work and is never destroyed, only converted from one form to another.
做功 W（单位焦耳 J）的计算公式为 W = F × d，其中 F 为力（牛顿），d 为沿力方向移动的距离。能量是做功的本领，它不会消失，只会从一种形式转化为另一种形式。
energy and t is time in seconds. Also, for vehicles moving at a constant speed, P = F × v.
功率 P（单位瓦特 W）衡量能量转换的速率：P = E / t，E 为能量，t 为时间（秒）。此外，对于匀速行驶的车辆，P = F × v。
inetic energy Eₖ = ½ m × v². In an ideal system, the total mechanical energy is conserved.
重力势能 Eₚ = m × g × h；动能 Eₖ = ½ m × v²。在理想系统中，总机械能守恒。
4. Simple Machines and Efficiency | 简单机械与效率
Levers, pulleys, and gears are mechanical systems that multiply force or change direction. The mechanical advantage (MA) is the ratio of output force to input force.
杠杆、滑轮和齿轮属于机械系统，可以放大力或改变力方向。机械效益（MA）是输出力与输入力之比。
compares the distance moved by the effort to the distance moved by the load. Efficiency (%) = (useful work output / total energy input) × 100% = MA / VR × 100%.
速比（VR）比较动力端移动的距离与负载端移动的距离。效率 (%) = (有用功输出 / 总能量输入) × 100% = MA / VR × 100%。
No machine can have an efficiency of 100% in practice due to friction and energy losses, which often appear as heat or sound.
在现实中，由于摩擦和能量损失（常以热或声的形式散失），没有任何机械能够达到 100% 的效率。
5. Material Properties and Selection | 材料性能与选择
Materials are grouped into metals, polymers, ceramics, and composites. Key mechanical properties include strength, hardness, toughness, ductility, stiffness, and density.
材料分为金属、聚合物、陶瓷和复合材料。主要力学性能包括强度、硬度、韧性、延展性、刚度和密度。
Electrical conductors (copper, aluminium) have low resistivity; insulators (PVC, glass) greatly resist current flow. Thermal conductivity is vital for heat exchangers and cooling systems.
电导体（铜、铝）电阻率低；绝缘体（PVC、玻璃）极大地阻碍电流。导热性对热交换器和散热系统至关重要。
Engineers select materials by matching properties to functional requirements and considering cost, availability, and environmental impact. Composite materials combine the best properties of their constituents.
工程师依据功能需求匹配材料性能，并综合考虑成本、可获得性及环境影响来选择材料。复合材料能够结合各组分的优良性能。
6. Electronics Fundamentals: Ohm's Law and Circuits | 电子学基础：欧姆定律与电路
Ohm' rtional to the current I flowing through it: V = I × R, where R is resistance in ohms (Ω).
欧姆定律指出，电阻两端的电压 V 与流过电阻的电流 I 成正比：V = I × R，其中 R 为电阻值（欧姆 Ω）。
allel: 1/Rₜ = 1/R₁ + 1/R₂ + ... . In parallel, the voltage across each branch is the same.
串联电路总电阻 Rₜ = R₁ + R₂ + ... 。并联电路总电阻：1/Rₜ = 1/R₁ + 1/R₂ + ... 。并联电路中，各支路两端电压相等。
tor colour codes indicate resistance value and tolerance. A potential divider uses two resistors to obtain a fraction of the input voltage.
电功率 P = V × I = I² × R。电阻色环码标示阻值与误差。分压器利用两只电阻获得输入电压的一部分。
7. Digital Electronics and Logic Gates | 数字电子学与逻辑门
Logic gates process binary signals (0 or 1). The basic gates are NOT, AND, and OR, from which NAND and NOR can be derived. Truth tables list all possible input combinations and corresponding outputs.
逻辑门处理二进制信号（0 或 1）。基本门包括非门、与门和或门，进而可组合出与非门和或非门。真值表列出所有输入组合及对应输出。
A NAND gate gives an output of 0 only when all inputs are 1. The combination of NAND gates can create any logic function, making them universal gates.
与非门仅在全部输入为 1 时输出 0。仅用与非门便可实现任何逻辑功能，因此它是通用门。
Simple electronic control circuits often use switches, transistors, and relays. A transistor can function as an electronic switch, amplifying a small base current to control a larger collector current.
简单的电子控制电路常使用开关、晶体管和继电器。晶体管可用作电子开关，以较小的基极电流放大并控制较大的集电极电流。
8. Structures and Stress Analysis | 结构与应力分析
A structure must resist applied loads without collapsing or deforming excessively. The main types of force are tension, compression, shear, torsion, and bending.
结构必须能够承受施加的载荷，而不发生倒塌或过度变形。力的主要类型有拉伸、压缩、剪切、扭转和弯曲。
measured in pascals (Pa). Strain ε = change in length / original length (no units). Young's modulus E = stress / strain for elastic materials.
应力 σ = F / A（力除以面积），单位为帕斯卡 Pa。应变 ε = 长度变化量 / 原始长度（无单位）。对于弹性材料，杨氏模量 E = 应力 / 应变。
Beams and frames are designed to minimize bending moments. The factor of safety is the ratio of the ultimate (breaking) stress to the allowable working stress, ensuring reliability.
梁与框架的设计旨在最小化弯矩。安全系数是极限（断裂）应力与许用工作应力之比，用以保证可靠性。
9. Introduction to Pneumatic and Hydraulic Systems | 气动与液压系统入门
Pneumatic systems use compressed air to transmit and control power, while hydraulic systems use an incompressible fluid (oil). Both systems can generate linear or rotary motion via actuators.
气动系统使用压缩空气传递和控制动力，液压系统则利用不可压缩的流体（液压油）。两者均可通过执行器产生直线或旋转运动。
Key components include a compressor or pump, valves (directional control, flow control), cylinders, and motors. Symbolic circuit diagrams are used to represent these components in a standardized way.
关键部件包括压缩机或泵、阀（方向控制阀、流量控制阀）、气缸和马达。标准化的符号回路图用于表示这些组件。
Pascal's principle states that pressure applied to a confined fluid is transmitted equally in all directions. This allows hydraulic systems to achieve large force multiplication (e.g., car brakes).
帕斯卡原理指出，施加于密闭流体的压强会等大地向各个方向传递。这使得液压系统可以实现巨大的力放大效果（如汽车制动）。
10. Engineering Design and Communication | 工程设计与沟通
The engineering design cycle includes identifying needs, researching, developing ideas, producing a solution, testing, and evaluating. Sustainability and ethical considerations are increasingly important in modern design.
工程设计循环包括识别需求、调研、构思方案、制作、测试与评估。可持续性与道德考量在现代设计中日益重要。
Technical drawings (orthographic projections, isometric views) and CAD models communicate design intent precisely. Dimensions, tolerances, and material specifications must be clear.
工程图（正投影图、等轴测图）和 CAD 模型用于精确传达设计意图。尺寸、公差与材料规格必须清晰明确。
Prototyping, whether physical or virtual, helps identify flaws early. Designers also consider the product's lifecycle, from raw material extraction to disposal or recycling.
物理或虚拟原型制作有助于尽早发现缺陷。设计者还需考虑产品从原材料获取到废弃或回收的整个生命周期。
11. Drive Systems and Motion Conversion | 驱动系统与运动转换
Belt and pulley systems transmit rotary motion between shafts, with speed ratios given by pulley diameters. Gears (spur, bevel, worm) provide precise speed and torque changes.
带轮系统在轴之间传递旋转运动，转速比由带轮直径决定。齿轮（直齿轮、锥齿轮、蜗轮蜗杆）提供精确的转速与扭矩变化。
A crank and slider mechanism converts rotary motion to linear reciprocating motion, as used in engines. A rack and pinion changes rotary motion into linear motion (steering).
曲柄滑块机构将旋转运动转换为直线往复运动，常用于发动机。齿轮齿条机构则将旋转运动变为直线运动（转向系统）。
The speed ratio of a simple gear train is the product of the teeth on the driven gears divided by the product of the teeth on the driver gears. Compound gear trains achieve larger ratios in a compact space.
简单齿轮系的速比是从动轮齿数乘积除以主动轮齿数乘积。复式轮系可以在紧凑空间内实现大速比。
12. Control Systems and Programming Concepts | 控制系统与编程概念
Microcontrollers (like Arduino or PIC) can be programmed to respond to sensors (temperature, light, pressure) and control outputs such as LEDs, motors, or relays. Flowcharts help plan the sequence of operations.
微控制器（如 Arduino 或 PIC）可通过编程来响应传感器（温度、光、压力）并控制输出，如 LED、马达或继电器。流程图帮助规划操作顺序。
Open-loop control uses no feedback and operates purely on pre-set instructions. Closed-loop control uses sensor feedback to adjust the output continuously for greater precision.
开环控制不使用反馈，仅依赖预设指令运行。闭环控制则利用传感器反馈不断调节输出，以获得更高精度。
Basic programming constructs include sequence, selection (if-else), and iteration (loops). These are applied in engineering to automate processes and improve efficiency.
基本编程结构包括顺序、选择（if-else）和循环。这些在工程中用于实现过程自动化并提高效率。
Published by TutorHao | Engineering Revision Series | aleveler.com
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