📚 Case Study Practical Exercises for SQA Engineering | Year 10 案例分析实战演练
Engineering case studies are a core component of the SQA Engineering Science course at Year 10 level. They challenge you to apply theoretical knowledge to real‑world scenarios, just like a professional engineer would. In this article, we will walk you through a series of practical exercises designed to strengthen your analytical skills, technical understanding, and ability to present solutions clearly.
工程案例分析是 Year 10 阶段 SQA 工程科学课程的核心组成部分。它们要求你像专业工程师一样，将理论知识应用于实际场景。在本文中，我们将通过一系列实战练习，帮助你增强分析能力、技术理解力和清晰呈现解决方案的能力。
1. Introduction to Engineering Case Studies | 工程案例分析简介
In SQA Engineering, case studies often present a problem that integrates multiple areas – mechanics, electronics, materials, and systems. You are expected to recognise the key engineering principles at play, gather relevant data, perform calculations, and justify your decisions. The exercises below mirror the style and depth of actual SQA assessments.
在 SQA 工程中，案例分析通常融合多个领域——机械、电子、材料和系统。你需要识别关键工程原理，收集相关数据，进行计算，并论证你的决策。以下练习模拟了真实 SQA 评估的风格和深度。
Keep in mind that marks are awarded not only for correct answers but also for showing working steps and logical reasoning. Always structure your response so that an examiner can follow your thought process without effort.
请记住，分数不仅给正确答案，还给展示解题步骤和逻辑推理的过程。始终将你的回答结构清晰，让考官能毫不费力地跟上你的思路。
2. Understanding the Design Brief | 理解设计任务书
A design brief is the starting point for any engineering project. Suppose you receive a brief to design a portable solar‑powered phone charger for hikers. The brief states: "The device must charge a smartphone to 50% capacity using only sunlight within 4 hours. It must weigh less than 200 g and withstand light rain. Total manufacturing cost should not exceed £15."
设计任务书是任何工程项目的起点。假设你收到一份任务书，要求为远足者设计一款便携式太阳能手机充电器。任务书说明：“该设备必须仅依靠阳光，在 4 小时内将智能手机充至 50% 电量。重量须低于 200 克，并能承受小雨。总制造成本不超过 15 英镑。”
Your first job is to highlight the functional requirements (must‑haves) and separate them from desirables. In this case, charging performance, weight, weather resistance, and cost are all hard constraints. Identify the trade‑offs: a larger solar panel charges faster but increases weight and cost.
你的第一项工作是标出功能需求（必须满足的）并将它们与期望特征分开。在本案例中，充电性能、重量、耐候性和成本都是硬性约束。找出权衡点：更大的太阳能板充电更快，但会增加重量和成本。
Once the constraints are clear, list the engineering disciplines involved – photovoltaics, battery technology, casing materials, and manufacturing processes. This initial analysis helps you plan the investigation logically.
一旦约束条件清晰，列出涉及的工程学科——光伏技术、电池技术、外壳材料和制造工艺。这一初步分析有助于你合理规划研究过程。
3. Materials Selection in Context | 材料选择的实际应用
Engineers rarely have unlimited material choices. Imagine you are selecting a material for a bicycle frame to be used in city commuting. Three candidates are available: low‑carbon steel, aluminium alloy (6061), and carbon‑fibre‑reinforced polymer. You need to compare density, tensile strength, relative cost, and ease of recycling.
工程师很少有无限的材料选择。想象你正在为城市通勤自行车选择车架材料。有三种候选材料：低碳钢、铝合金 6061 和碳纤维增强聚合物。你需要比较密度、抗拉强度、相对成本和可回收性。
| Property | Low‑carbon steel | Al alloy 6061 | Carbon fibre composite |
| Density (kg/m³) | 7850 | 2700 | 1600 |
| Tensile strength (MPa) | 250 | 310 | 600 |
| Relative cost per kg | Low (1x) | Medium (3x) | High (15x) |
| Recyclability | Excellent | Very good | Difficult |
Steel is heavy but cheap and infinitely recyclable; carbon fibre offers the best strength‑to‑weight ratio but is expensive and hard to recycle. Aluminium sits in the middle. A city bike that needs to be affordable and durable would likely use steel or aluminium. The final decision must be justified with clear reasoning linked to the design brief.
钢虽然重但便宜且可无限回收；碳纤维提供最佳的强度重量比但昂贵且难以回收；铝合金则居中。一辆需要经济实惠且耐用的城市自行车很可能会使用钢或铝合金。最终决定必须用与设计任务书相关的清晰推理来论证。
4. Structural Analysis: Bridge Case Study | 结构分析：桥梁案例
Consider a simple truss footbridge made of steel tubes. The bridge span is 8 m and it must support a maximum point load of 2 kN at the centre. The truss has two top chords, two bottom chords, and diagonal braces forming equilateral triangles. Your task is to determine the tensile force in one bottom chord member.
考虑一座由钢管构成的简易桁架人行桥。桥跨度为 8 米，必须支撑中心处最大 2 千牛的集中荷载。桁架有两条上弦杆、两条下弦杆和构成等边三角形的斜腹杆。你的任务是确定一根下弦杆的拉力。
Start by drawing a free‑body diagram and applying static equilibrium equations. Taking moments about one support, the vertical reaction at each end is 1 kN. Then isolate a joint using method of joints. For a joint where only a bottom chord, a diagonal, and the reaction meet, use force equilibrium.
首先绘制受力图并应用静力平衡方程。取对一支座的力矩，每个端部的竖向反力为 1 千牛。然后用节点法隔离一个节点。对于仅有下弦杆、斜杆和反力交汇的节点，应用力的平衡。
ΣFy = 0 → Fdiagonal × sin 60° = 1 kN
Solving gives the diagonal force, and then horizontal equilibrium ΣFx = 0 yields the bottom chord tension. Usually the bottom chord carries a large tensile force. Mention that slenderness ratio could cause buckling in compression members, so diagonals are often thicker.
求解得斜杆内力，然后水平平衡方程 ΣFx = 0 得出下弦杆拉力。通常下弦杆承受较大拉力。要指出长细比可能导致受压杆件屈曲，因此斜杆往往更粗。
5. Electronic Circuit Troubleshooting | 电子电路故障排查
A student builds an LED indicator circuit using a 9 V battery, a red LED (forward voltage 2 V, rated current 20 mA), and a resistor. When powered, the LED is dim and the resistor feels very hot. Use your electronics knowledge to diagnose the fault.
一名学生用 9 伏电池、一个红色 LED（正向电压 2 伏，额定电流 20 毫安）和一个电阻搭建了一个 LED 指示灯电路。上电后，LED 很暗且电阻摸起来非常烫。请用你的电子学知识诊断故障。
First calculate the correct series resistance using Ohm's law. The voltage across the resistor should be 9 V – 2 V = 7 V. For a current of 20 mA (0.02 A), the required resistance is R = V / I = 7 V / 0.02 A = 350 Ω. The power dissipated in the resistor is P = I²R = (0.02)²; × 350 = 0.14 W, so a standard 0.25 W resistor would work.
首先用欧姆定律计算正确的串联电阻。电阻两端的电压应为 9 V – 2 V = 7 V。对于 20 mA（0.02 A）的电流，所需电阻为 R = V / I = 7 V / 0.02 A = 350 Ω。电阻消耗的功率为 P = I²R = (0.02)²; × 350 = 0.14 W，因此标准 0.25 W 电阻即可。
The dim LED and hot resistor suggest the resistor value is far too low, perhaps 35 Ω instead of 350 Ω. A lower resistance causes excessive current, overheating the resistor and starving the LED of the correct voltage drop. Always double‑check colour codes or measure with a multimeter.
LED 暗淡而电阻发烫，表明电阻值过小，可能是 35 Ω 而非 350 Ω。过低电阻导致电流过大，电阻过热同时使 LED 无法获得正确压降。务必复查色环编码或用万用表测量。
6. Mechanical Systems: Gear Ratios | 机械系统：齿轮比计算
Gear systems are common in bicycles and machinery. A mountain bike has a chainring with 44 teeth and a rear sprocket with 11 teeth. Calculate the gear ratio and the speed of the rear wheel when the rider pedals at 80 revolutions per minute (rpm).
齿轮系统在自行车和机械中十分常见。一辆山地车的牙盘有 44 齿，后飞轮有 11 齿。请计算齿轮比以及骑行者以 80 转每分钟（rpm）踩踏时后轮的速度。
Gear ratio = driven teeth / driver teeth = 44 / 11 = 4 : 1. speed = 80 × 4 = 320 rpm. If the wheel diameter is 0.7 m, you can also find the bike's linear speed.
齿轮比 = 从动轮齿数 / 主动轮齿数 = 44 / 11 = 4 : 1。这意味着曲柄每转一圈，后轮转四圈。因此曲柄转速 80 rpm 时，后轮转速 = 80 × 4 = 320 rpm。如果车轮直径为 0.7 米，还可求自行车线速度。
Remember that a high gear ratio increases speed but requires greater torque from the rider. In an engineering case study you might be asked to discuss the trade‑off between speed and climbing ability, linking gear selection to the terrain described in the brief.
记住高齿轮比提升速度但要求骑行者输出更大扭矩。在工程案例分析中，你可能会被要求讨论速度与爬坡能力之间的权衡，并将齿轮选择与任务书中描述的地形联系起来。
7. Energy Efficiency in a Wind Turbine | 风机能效分析
An energy company is testing a small wind turbine with a blade diameter of 2 m. On a day with wind speed 10 m/s and air density 1.225 kg/m³, the turbine generates 600 W of electrical power. Determine its efficiency and comment on the result.
一家能源公司正在测试一台叶片直径为 2 米的小型风力发电机。在风速 10 米/秒、空气密度 1.225 千克/立方米的日子里，发电机输出 600 瓦电功率。请确定其效率并评论结果。
The swept area A = π × (d/2)² = π × 1² = 3.14 m²;. The theoretical wind power is given by:
Pwind = ½; ρ A v³
Substituting values: Pwind × 3.14 × 10³ = 0.5 × 1.225 × 3.14 × 1000 ≈ 1924 W. Efficiency = (600 / 1924) × 100% ≈ 31.2%.
代入数值：P风 × 3.14 × 10³ = 0.5 × 1.225 × 3.14 × 1000 ≈ 1924 W。效率 = (600 / 1924) × 100% ≈ 31.2%。
This is a realistic figure, as the Betz limit states that no turbine can capture more than about 59% of the kinetic energy in the wind. The rest is lost in the wake, gearbox, and generator. In your case study, discuss ways to improve efficiency, such as better blade aerodynamics, reducing friction in bearings, or installing a gearbox with a suitable ratio.
这是现实可行的数字，因为贝茨极限表明没有涡轮机可以从风中捕获超过约 59% 的动能。其余能量在尾流、齿轮箱和发电机中损失。在你的案例分析中，讨论提高效率的方法，如改善叶片气动性能、减少轴承摩擦或安装合适速比的齿轮箱。
8. Programming a Microcontroller for a Product | 为产品编程微控制器
Many modern devices use microcontrollers. A case study might ask you to design a simple program for an Arduino that automatically opens a greenhouse vent when the temperature exceeds 28 °C. A temperature sensor (LM35) gives an analogue voltage proportional to temperature (10 mV/°C).
许多现代设备使用微控制器。案例分析可能要求你为 Arduino 设计一个简单程序，当温度超过 28 °C 时自动打开温室通风口。一只温度传感器 LM35 输出与温度成正比（10 毫伏/度）的模拟电压。
You need to read the analogue value, convert it to temperature, compare with a set point, and turn a servo motor to open the vent. Provide pseudo‑code and explain how the output pins control the actuator. This demonstrates systems thinking – combining electronics, programming, and mechanics.
你需要读取模拟值，转换为温度，与设定点比较，并转动伺服电机打开通风口。提供伪代码并解释输出引脚如何控制执行器。这体现了系统思维——结合电子、编程和机械。
- Read analogue pin A0, store value in 'sensorValue'.
- Convert to voltage: voltage = sensorValue * (5.0 / 1023).
- Convert to temperature: tempC = voltage * 100.
- If tempC > 28, set servo to 90 degrees (open); else set to 0 degrees (close).
In your analysis, mention the importance of calibration, hysteresis to prevent rapid on/off cycling, and fail‑safe behaviour if the sensor fails.
在你的分析中，提到校准的重要性、防止快速开关节奏的迟滞控制以及传感器失效时的故障安全行为。
9. Quality Control and Testing | 质量控制与测试
When a company mass‑produces metal brackets, each must have a length of 50.0 mm with a tolerance of ±0.3 mm. A sample of five brackets from one batch shows lengths (mm): 50.1, 49.9, 50.4, 49.8, 50.2. Determine whether the batch meets the specification and calculate the mean and range.
当一家公司大批量生产金属支架，每件长度必须为 50.0 毫米，公差为 ±0.3 毫米。从一批次中抽检五个支架，测得长度（毫米）为：50.1, 49.9, 50.4, 49.8, 50.2。判断该批次是否符合规格，并计算均值和极差。
Mean = (50.1 + 49.9 + 50.4 + 49.8 + 50.2) / 5 = 50.08 mm. Range = 50.4 – 49.8 = 0.6 mm. All values lie within 49.7–50.3 mm? Actually, 50.4 mm is above the upper limit of 50.3 mm, so this batch fails! Even though the range is 0.6 mm, the presence of an out‑of‑spec item means the process needs adjustment.
均值 = (50.1 + 49.9 + 50.4 + 49.8 + 50.2) / 5 = 50.08 毫米。极差 = 50.4 – 49.8 = 0.6 毫米。所有数值是否落在 49.7–50.3 毫米内？实际上 50.4 毫米超出了上限 50.3 毫米，因此该批次不合格！尽管极差为 0.6 毫米，超差件的出现意味着制程需要调整。
In a case study, you should suggest actions such as checking the cutting tool wear, recalibrating the measurement instrument, or increasing sample size. Emphasise the difference between accuracy and precision using a simple sketch.
在案例分析中，你应提出行动建议，如检查刀具磨损、重新校准量具或增大样本量。用简单示意图强调准确度与精密度的区别。
10. Presenting Your Findings | 呈现你的研究结果
SQA examiners expect a well‑structured report even for practical case studies. Use clear headings, labelled diagrams, and tables where appropriate. Start with a brief introduction, state the problem, describe your method, present calculated results, and finish with a justified conclusion.
SQA 考官期望即使是实际案例分析也要有结构清晰的报告。使用明确的标题、标注的图示，并在适当处使用表格。以简短引言开头，陈述问题，描述方法，呈现计算结果，并以有理有据的结论结尾。
Diagrams do not need to be artistic but must be neat and correctly annotated. For a bridge truss, label forces with arrows and show dimensions. For a circuit, draw the schematic using standard symbols. Ensure every graph has title, axis labels, and units.
图表不需要美轮美奂，但必须整洁且正确标注。对桥梁桁架，用箭头标注力并标明尺寸。对电路，使用标准符号绘制原理图。确保每张图都有标题、轴标签和单位。
11. Review of Common Mistakes | 常见错误检视
Many students lose easy marks by forgetting units, mixing up mass and weight, or using the wrong formula for power calculations. In a mechanical problem, if you write final force as '150', without Newtons, the answer is meaningless. Always include the correct SI unit after every value.
许多学生因忘记标单位、混淆质量和重量，或在功率计算中误用公式而丢失了本应得的分数。在力学问题中，若最终力只写“150”而没有牛顿，答案就毫无意义。始终在每个数值后加上正确的国际单位。
Another frequent error is copying numbers from a data sheet without considering whether they are applicable. For example, tensile strength values in a table are for standard test specimens; the actual component may behave differently due to shape or size. Always comment on limitations and safety factors.
另一个常见错误是从数据表中照搬数值而不考虑其是否适用。例如，表格中的抗拉强度数值是针对标准试样的；实际构件因形状或尺寸不同可能性能有异。务必说明局限性和安全系数。
12. Final Tips for SQA Engineering Case Studies | SQA 工程案例分析终极建议
Treat each case study as a mini engineering project. Read the brief three times – first for general understanding, second to underline numerical data, third to note the marks allocated per part. Let the mark allocation guide how much detail to provide.
将每个案例分析视为一个小型工程项目。阅读任务书三遍——第一遍了解大意，第二遍划出数字数据，第三遍注意每部分的分值分配。让分值引导你提供多少细节。
Practice with past paper scenarios and timing yourself. Learn to perform quick estimation to sense‑check your calculated answers. If you calculate a gear ratio of 0.8 for a bicycle that should go fast, you have probably swapped driver and driven gears.
用往年考题情景练习并计时。学会快速估算，以感觉检验你的计算结果。如果你为一辆应能快速行驶的自行车计算出齿数比为 0.8，你可能把主动轮和从动轮弄反了。
Finally, remember that engineering is about solving problems within constraints. There is rarely a single perfect answer – examiners reward a logical, well‑documented approach even if the final number is slightly off due to a minor arithmetic slip. Show your thinking proudly.
最后，记住工程学是在约束条件下解决问题。几乎不存在唯一的完美答案——即使最终数字因小算术失误稍有偏差，考官仍会奖励逻辑清晰、记录完善的方法。自豪地展示你的思考过程。
Published by TutorHao | Engineering Revision Series | aleveler.com
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