Engineering Admissions Assessment 2018 Section 2 Question Paper | 工程入学评估 2018 第二部分试卷精讲

📚 Engineering Admissions Assessment 2018 Section 2 Question Paper | 工程入学评估 2018 第二部分试卷精讲

The Engineering Admissions Assessment (EAA, formerly ENGAA) Section 2 is the advanced physics paper used by the University of Cambridge to distinguish strong engineering applicants. The 2018 question paper is an excellent resource for A-Level students because it tests problem-solving under tight time pressure, not just recall of equations. This article breaks down the 2018 Section 2 paper, explains the key topics, works through typical questions, and offers a revision strategy.

工程入学评估（EAA，前身为 ENGAA）第二部分是剑桥大学用来区分优秀工程申请者的高级物理试卷。2018 年的试卷对 A-Level 学生来说是极好的复习资源，因为它考查的是在紧张时间压力下解决问题的能力，而不仅仅是回忆公式。本文将拆解 2018 年第二部分试卷，解释关键专题，演练典型题目，并提供复习策略。

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1. Overview of the 2018 Section 2 Paper | 2018 年第二部分试卷概览

The 2018 Section 2 paper consists of 20 multiple-choice questions to be completed in 60 minutes. This gives an average of three minutes per question. Unlike Section 1, where questions cover broad mathematics and physics, Section 2 focuses on advanced physics topics that require multi-step reasoning. The paper is designed so that a strong candidate can score well by applying A-Level concepts in unfamiliar contexts.

2018 年第二部分试卷包含 20 道选择题，要求在 60 分钟内完成。平均每题只有三分钟。与第一部分覆盖广泛数学和物理知识不同，第二部分聚焦于需要多步推理的高级物理专题。试卷的设计意图是让基础扎实的考生能够通过将 A-Level 概念应用于不熟悉的情境来取得高分。

The format is entirely multiple choice, so there is no credit for showing working. This means accurate mental arithmetic, algebraic manipulation, and quick recognition of the correct physical principle are essential. Many students find Section 2 more challenging than Section 1 because the questions often combine two or more areas of physics in a single problem.

试卷完全采用选择题形式，因此不展示解题过程就没有分数。这意味着准确的心算、代数运算以及对正确物理原理的快速识别至关重要。许多学生发现第二部分比第一部分更具挑战性，因为题目常常将两个或更多物理领域结合在一个问题中。

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2. Advanced Physics Topics in Section 2 | 第二部分考查的高级物理专题

The 2018 Section 2 syllabus is not published as a separate list, but past papers show consistent coverage of mechanics, electric circuits, materials, waves, and thermal physics. Within mechanics, topics include projectile motion, circular motion, momentum, energy, and simple harmonic motion. Electric circuits may involve Kirchhoff’s laws, capacitors, potential dividers, and internal resistance. Materials questions often test Young modulus, stress, strain, and elastic potential energy. Waves include superposition, interference, and standing waves. Thermal physics questions can cover ideal gases and specific heat capacity.

2018 年第二部分并没有单独发布考纲，但历年试卷显示其稳定涵盖力学、电路、材料、波动和热学。力学部分包括抛体运动、圆周运动、动量、能量以及简谐运动。电路部分可能涉及基尔霍夫定律、电容器、分压器和内阻。材料题通常考查杨氏模量、应力、应变和弹性势能。波动包括叠加、干涉和驻波。热学题可能涉及理想气体和比热容。

• Mechanics / 力学: projectile motion, circular motion, momentum / 抛体运动、圆周运动、动量
• Electric circuits / 电路: Kirchhoff’s laws, capacitors, internal resistance / 基尔霍夫定律、电容器、内阻
• Materials / 材料: Young modulus, stress-strain, elastic energy / 杨氏模量、应力应变、弹性能
• Waves / 波动: superposition, interference, standing waves / 叠加、干涉、驻波
• Thermal physics / 热学: ideal gas, specific heat capacity / 理想气体、比热容

Questions often blur the boundaries between these topics. For example, a thermal physics question may require using mechanics concepts such as pressure and force, or a waves question may involve wave speed on a string under tension. The 2018 paper rewarded candidates who could recognise the relevant principle from a mixed context.

题目常常模糊这些专题之间的界限。例如，热学题可能需要用到压力和力等力学概念，波动题可能涉及弦在张力下的波速。2018 年试卷青睐能够从混合情境中识别相关原理的考生。

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3. Skills Assessed by the 2018 Paper | 2018 年试卷评估的技能

Section 2 is not just about knowing formulas. The 2018 paper rewards candidates who can translate a written problem into a diagram, select the correct physical principle, manipulate equations accurately, and interpret graphs or data tables. Many questions combine two or more topics, such as energy conservation with electricity or circular motion with forces.

第二部分不仅仅是会背公式。2018 年试卷青睐那些能够将文字题转化为示意图、选择正确物理原理、准确处理方程并解读图像或数据表的考生。许多题目将两个或更多专题结合起来，例如能量守恒与电路结合，或圆周运动与力的结合。

The multiple-choice format means that the wrong options are carefully chosen to trap common errors. For instance, a projectile motion question may offer options that correspond to using the vertical component instead of the horizontal component, or forgetting the factor of one-half in the kinematic equation. You need to be alert to these distractors.

选择题形式意味着错误选项是精心设计的，用来诱使常见错误。例如，抛体运动题可能给出使用竖直分量而不是水平分量、或者忘记运动学方程中二分之一系数的选项。你需要对这些干扰项保持警惕。

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4. Worked Example 1 – Projectile Motion | 例题 1 – 抛体运动

A typical projectile question from the 2018 Section 2 might ask you to find the horizontal range of a ball thrown from a height h with initial speed u at an angle θ above the horizontal. The key is to split the motion into horizontal and vertical components. The horizontal component of velocity is u cos θ, and the vertical component is u sin θ. Use the vertical motion to find the time of flight, then multiply by the horizontal velocity.

2018 年第二部分中一道典型的抛体题可能会要求你求出一个小球从高度 h 处以初速度 u、与水平方向成 θ 角向上抛出后的水平射程。关键是将运动分解为水平和竖直两个分量。水平速度分量为 u cos θ，竖直速度分量为 u sin θ。先用竖直运动求出飞行时间，再乘以水平速度。

If the ball lands at the same height, time of flight is t = 2u sin θ / g, and range is R = u cos θ × t, giving:

如果小球落回同一高度，飞行时间为 t = 2u sin θ / g，射程为 R = u cos θ × t，即：

R = (u² sin 2θ) / g

If the landing height is different, use the full equation s = ut + ½at² for vertical displacement, solve the quadratic for time, and substitute into the horizontal equation x = uₓ t. Be careful with the sign of the vertical displacement: if the ball falls below the starting point, s is negative.

如果落点高度不同，则使用完整的竖直位移方程 s = ut + ½at²，求解关于时间的二次方程，再代入水平方程 x = uₓ t。注意竖直位移的符号：如果小球落到出发点下方，s 为负值。

In the 2018 paper, projectile questions often included an initial height or a landing point at a different level, forcing you to solve a quadratic equation rather than simply using the range formula. Always sketch the trajectory and label the initial and final positions.

在 2018 年试卷中，抛体题常常包含初始高度或不同高度的落点，迫使你求解二次方程，而不是简单套用射程公式。务必画出轨迹图，并标出初末位置。

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5. Worked Example 2 – Electrical Power and Resistance | 例题 2 – 电功率与电阻

Section 2 often includes circuit questions where a cell with internal resistance is connected to an external resistor. For example, a cell of emf ε and internal resistance r is connected to a variable resistor R. The current in the circuit is I = ε / (R + r). The power delivered to the external resistor is P = I²R.

第二部分经常包含电路题，如一个具有内阻的电池连接到外部电阻。例如，一个电动势为 ε、内阻为 r 的电池连接到一个可变电阻 R。电路中的电流为 I = ε / (R + r)。传递给外部电阻的功率为 P = I²R。

By substituting the expression for current, the power becomes:

将电流表达式代入后，功率变为：

P = ε² R / (R + r)²

By differentiating P with respect to R and setting the derivative to zero, you can show that maximum power transfer occurs when R = r. This is a classic result that appeared in the 2018 paper style. When R is much greater than r, the terminal pd is close to the emf; when R equals r, the terminal pd is half the emf, and the efficiency is 50%.

通过对 P 关于 R 求导并令导数为零，可以证明最大功率传输发生在 R = r 时。这是 2018 年试卷风格中出现的经典结论。当 R 远大于 r 时，路端电压接近电动势；当 R 等于 r 时，路端电压为电动势的一半，效率

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