AS Physics Unit 1 Mark Scheme Jan19: Application Question Techniques | AS 物理单元1 2019年1月评分标准：应用题答题技巧

📚 AS Physics Unit 1 Mark Scheme Jan19: Application Question Techniques | AS 物理单元1 2019年1月评分标准：应用题答题技巧

This article explores the mark scheme from the AS Physics Unit 1 January 2019 examination, focusing on how to approach application questions effectively. We will break down the common command words, the structure of model answers, key terms that secure marks, and the typical pitfalls to avoid. Whether you are revising mechanics, materials, or wave behaviour, mastering the mark scheme is the most direct route to turning your physics knowledge into high exam scores.

本文深度解析 AS 物理单元1 2019年1月考试的评分标准，重点讲解如何高效应对应用题。我们将拆解常见的指令词、标准答案的结构、确保得分的关键术语，以及需要避免的典型错误。无论你正在复习力学、材料还是波动行为，掌握评分标准是把物理知识转化为高分的最直接途径。

1. Understanding Command Words in Context | 在语境中理解指令词

In the January 2019 mark scheme, ‘State’ questions required a concise factual answer with no explanation. For instance, ‘State the principle of conservation of momentum’ needed only the exact wording from the specification. By contrast, ‘Explain’ meant linking a physical cause to an effect using correct terminology. Many students lost marks by providing a ‘State’-style answer when the question demanded an explanation.

在2019年1月的评分标准中，”陈述”（State）类问题需要简洁的事实性回答，无需解释。例如，”陈述动量守恒原理”只需写出考纲中的准确表述。相反，”解释”（Explain）类问题要求用正确的术语将物理原因与结果联系起来。许多学生失分是因为题目要求解释，他们却给出了”陈述”式的答案。

2. Showing Full Working in Calculations | 计算题展示完整步骤

Awarding of method marks in Unit 1 Jan19 was strict: every substitution, rearrangement, and unit conversion had to be explicit. A final correct answer without working earned only the answer mark, losing up to two method marks. Examiners rewarded clear layout—writing the formula in symbols first, substituting numbers, then calculating. Using the potential divider formula without showing V_out = V_in × (R2/(R1+R2)) would forfeit marks even if the final value was right.

2019年1月单元1中的方法分非常严格：每一步代入、公式变形和单位换算都必须明确写出。仅给出最终正确答案而没有计算过程，只能得到答案分，最多可能丢失两个方法分。阅卷人青睐清晰的版面——先用符号写出公式，再代入数字，最后计算。如果使用分压公式却不写出 V_out = V_in × (R2/(R1+R2))，即使最终数值正确也会失分。

3. Precision in Naming Forces and Directions | 准确命名力和方向

When a golf ball was struck by a club in a Jan19 application question, candidates were asked to draw a free-body diagram at the instant of impact. The mark scheme required arrows labelled ‘weight’ (or ‘gravity’), ‘normal reaction’ (or ‘contact force’), and ‘force from club’, all acting from the centre of mass. ‘Upward force’ or ‘air resistance’ were not accepted. Direction labels mattered: an arrow pointing downward without ‘weight’ earned zero. Always use the exact terms listed in the syllabus.

在2019年1月的一道应用题中，高尔夫球被球杆击中的瞬间，要求考生画出受力图。评分标准要求箭头分别标注”重力”（或”引力”）、”法向反作用力”（或”接触力”）和”球杆施加的力”，并且所有力都要从质心画出。写”向上的力”或”空气阻力”均不给分。方向标注也很关键：一个向下的箭头若不写”重力”就不得分。请务必使用考纲中列出的精确术语。

4. Using Proportionality and Graph Skills | 比例关系和图像分析技巧

The Jan19 paper featured a graph of extension against force for a rubber band. The mark scheme awarded marks for identifying the limit of proportionality, describing the curved region as ‘non-linear’, and stating that the band no longer obeys Hooke’s law. Marks were lost when students used vague phrases like ‘it stretches more’. A valid answer needed ‘force is no longer proportional to extension’ or ‘stiffness changes beyond this point’. Always link graphical features to the underlying physics law.

2019年1月的试卷中出现了橡皮筋的伸长量-拉力图像。评分标准对识别比例极限、将曲线区域描述为”非线性”、并说明橡皮筋不再遵循胡克定律的答案给分。学生使用”它拉得更长了”之类模糊表述就会失分。有效的回答必须包含”力不再与伸长量成正比”或”超过该点后劲度发生变化”。始终将图像特征与背后的物理定律联系起来。

5. Energy Conservation and Work-Energy Principle | 能量守恒与功能原理

An application question required calculating the speed of a pendulum bob at its lowest point using energy methods. The mark scheme accepted either ΔGPE = ΔKE or stating that work done by gravity equals gain in kinetic energy. Crucially, the height loss had to be derived from length and angle, not estimated. Marks were also reserved for stating the assumption of no air resistance or friction. A complete energy answer always ends with a comment on energy transfers—this tiny sentence can be worth a mark.

一道应用题要求利用能量方法计算摆锤在最低点的速度。评分标准接受 ΔGPE = ΔKE 的写法，或者陈述重力做的功等于动能的增量。非常关键的是，高度下降量必须通过摆长和角度推导得出，不能估算。此外，还有专门的分数留给陈述”忽略空气阻力或摩擦”这个假设。一个完整的能量类答案总是以描述能量转化的小句子结尾——这短短一句话就可能值一分。

6. Explaining Waves: Phase and Path Difference | 解释波动：相位差和波程差

In a double-slit interference question, students had to explain why a bright fringe forms. The Jan19 mark scheme demanded reference to constructive interference, waves arriving in phase, and path difference being zero or a whole number of wavelengths. Answers missing the phrase ‘in phase’ scored a maximum of one out of two. Merely saying ‘the waves meet’ earned nothing. Always include the core physics mechanism—superposition and phase conditions—when explaining wave phenomena.

在双缝干涉问题中，学生需要解释亮条纹的形成原因。2019年1月的评分标准要求提及相长干涉、波同相到达、以及波程差为零或波长的整数倍。漏掉”同相”一词的答案最多只能得1分（满分2分）。仅仅说”波相遇”则完全不得分。解释波动现象时，务必包含核心物理机制——叠加和相位条件。

7. Material Properties: Stress, Strain and Young Modulus | 材料性质：应力、应变与杨氏模量

Application of the Young modulus formula required careful unit conversion. In Jan19, a wire’s diameter was given in mm; failing to convert to metres and to use radius in A = πr² led to a power-of-ten error. The mark scheme awarded one mark for correct area calculation, one for stress (force/area), one for strain, and one for the final modulus with the correct unit Pa or N m⁻². Always check that your final unit matches the quantity—a dimensionless strain value given a unit would be marked wrong.

应用杨氏模量公式时需要进行仔细的单位换算。2019年1月的考题中，金属丝的直径以毫米为单位给出；若未转换为米、未使用半径来计算截面积 A = πr²，就会导致数量级错误。评分标准这样分配分值：正确计算截面积得1分，正确计算应力（力/面积）得1分，计算应变得1分，最终给出带正确单位 Pa 或 N m⁻² 的模量值得1分。务必检查最终单位是否与物理量一致——如果无量纲的应变值带上了单位，就会被判定错误。

8. Circuit Analysis and Internal Resistance | 电路分析及内电阻

A question asked to find the internal resistance of a cell using a graph of terminal p.d. against current. The mark scheme required recognising the gradient as –r, explaining that the y-intercept is the e.m.f., and stating that lost volts = Ir. Many candidates lost the explanation mark by failing to link the gradient to the internal resistance explicitly. A strong answer reads: ‘The gradient is negative and equals the internal resistance because V = ε – Ir, so the magnitude of the gradient is r.’

一道题要求利用端电压-电流图像求电池的内电阻。评分标准要求识别斜率为 –r，解释 y 轴截距是电动势，并说明内电压损耗 = Ir。许多考生因未能将斜率与内电阻明确联系起来而丢失解释分。一个有力的答案应当这样写：”斜率为负且等于内电阻，因为 V = ε – Ir，所以斜率的绝对值就是 r。”

9. Combining Resistors and Potential Dividers | 电阻组合与分压器

When a thermistor and a fixed resistor formed a potential divider, the Jan19 mark scheme rewarded stepwise reasoning: first, describe how the thermistor’s resistance changes with temperature; then, state how the share of voltage changes; finally, link this to the output. Simply writing ‘the voltage increases’ without mentioning the thermistor’s resistance change or the fixed resistor’s role received only partial marks. One mark was always reserved for quoting the potential divider equation in the explanation.

当热敏电阻与固定电阻组成分压器时，2019年1月的评分标准奖励逐步推理：首先描述热敏电阻的阻值如何随温度变化；然后说明电压分配如何变化；最后将变化与输出电压联系起来。只写”电压增大”而不提热敏电阻的阻值变化或固定电阻的作用，只能得到部分分数。解释中总有一分是留给引用分压公式的。

10. Evaluation and Experimental Uncertainties | 实验评估与不确定度

An application question on measuring g using a pendulum required discussion of uncertainties. The mark scheme looked for identifying the largest source of uncertainty (often reaction time in timing oscillations), suggesting a correct improvement (e.g., timing more oscillations, using a light gate), and linking it to the reduction in percentage error. Generic phrases like ‘be more careful’ gained no credit. Precision in naming the quantity affected and the specific technique for improvement is key.

一道关于用摆测量 g 的应用题要求讨论不确定度。评分标准寻找的是：识别出最大的不确定度来源（往往是计时时的反应时间），提出正确的改进方法（例如测量更多次摆动的时间，使用光闸），并将其与百分比误差的减小联系起来。”更加小心”之类的笼统表述不得分。准确地指出受影响的物理量以及具体的改进技术是关键。

11. Common Mistakes Revealed by the Mark Scheme | 评分标准揭示的常见错误

Across the Jan19 paper, recurring errors included: confusing scalar and vector quantities in momentum problems, using sine instead of cosine when resolving forces, forgetting to square the radius in circular area calculation, and omitting units in final answers for derived quantities. The mark scheme explicitly penalised missing units by withholding the answer mark. For ‘Show that…’ questions, many candidates started from the given value and manipulated backwards—this is not accepted unless the exam explicitly allows it. You must derive from first principles.

在整个2019年1月试卷中，反复出现的错误包括：在动量问题中混淆标量和矢量，分解力时该用余弦却用了正弦，计算圆面积时忘记将半径平方，以及推导量的最终答案缺少单位。评分标准明确规定，缺少单位要扣掉答案分。对于”证明……”类问题，许多考生从给定数值入手进行逆向推导——除非题目明确允许，否则不会被接受。你必须从基本原理出发进行推导。

Published by TutorHao | Physics Revision Series | aleveler.com

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