📚 IB Physics: Extended Response Question Strategies | IB物理：扩展论述题答题策略
Extended response questions in IB Physics test more than your ability to recall formulas. They assess how you construct a logical argument, apply concepts to unfamiliar contexts, and communicate with precise scientific language.
IB物理扩展论述题考查的不仅是回忆公式的能力。它们评估你如何构建逻辑论证、将概念应用于陌生情境，以及用严谨的科学语言进行表达。
These questions appear mainly in Paper 2 Section B, but similar skills are needed in Paper 3 data-analysis and option questions.
这类问题主要见于试卷二第二板块，但试卷三的数据分析与选考题目同样需要这些技能。
1. Understand Command Terms | 理解指令词
Every extended-response item begins with a command term. The IB uses these to define the depth of answer expected. 'State' requires a single fact; 'Explain' requires a reason; 'Discuss' requires a balanced argument.
每道扩展论述题都以指令词开头。IB用指令词界定期望答案的深度。"State"要求单一事实；"Explain"要求给出理由；"Discuss"要求展开平衡论证。
The most common higher-order command terms are 'explain', 'discuss', 'evaluate', and 'analyse'. Make sure you know the difference before entering the exam.
最常见的高级指令词包括"explain"、"discuss"、"evaluate"和"analyse"。进入考场前，你必须清楚它们之间的区别。
| Command Term | 中文 | Required Response |
|---|---|---|
| State | 陈述 | A concise fact or value with no explanation. |
| Define | 定义 | A precise meaning of a physical quantity. |
| Calculate | 计算 | Show working and give a numerical answer with units. |
| Determine | 求出 | Obtain a value from data, a graph, or reasoning. |
| Derive | 推导 | Start from basic equations and show all steps. |
| Explain | 解释 | Give a reason using physics principles. |
| Discuss | 讨论 | Give a balanced response, including strengths and limitations. |
| Evaluate | 评价 | Judge the validity of a statement using evidence. |
| Analyse | 分析 | Interpret data and relationships in a structured way. |
| Sketch | 画图 | Draw a graph with correct general shape and labelled axes. |
The command term also signals the required length. A one-mark 'state' question should not produce a long paragraph, while a six-mark 'evaluate' question needs a clear structure and a conclusion.
指令词还提示了所需篇幅。1分的"State"题不应该写成长段落，而6分的"Evaluate"题则需要清晰结构和结论。
2. Deconstruct the Question | 拆解题目
Underline quantities, target variables, and limiting words such as 'assuming no air resistance'. This tells you which equations and principles are relevant.
标出已知量、目标变量和限制语，如"假设无空气阻力"。这告诉你哪些方程和原理是相关的。
Ask yourself: What is the physical situation? What principle governs it? What evidence or data do I need to use?
问自己：这是什么物理情境？控制它的原理是什么？我需要使用哪些证据或数据？
For example, a question about a satellite moving in a circular orbit contains the hidden condition that the gravitational force provides the centripetal force.
例如，一道关于卫星圆轨道运动的问题隐含了条件：万有引力提供向心力。
GMm/r² = mv²/r
If you can identify this hidden condition, the rest of the question becomes a straightforward substitution.
如果你能识别这个隐含条件，题目的其余部分就变成了简单的代入计算。
3. Plan Your Response | 规划作答
A good extended response is planned in about thirty seconds. Write brief bullet points in the answer space: definition, law, application, calculation, limitation.
好的扩展回答只需约30秒规划。在答题区写简短的要点：定义、定律、应用、计算、局限。
Use a simple framework to keep your answer logical.
使用一个简单框架来保持答案的逻辑性。
State the relevant physical principle. 陈述相关的物理原理。
Define symbols and write the general equation. 定义符号并写出一般方程。
Substitute data with correct units. 代入带有正确单位的数据。
Calculate and interpret the result. 计算结果并解释其物理含义。
State any assumptions or limitations. 说明任何假设或局限。
This structure ensures that even if your final calculation has a small error, you can still earn method and reasoning marks.
这样的结构确保即使最终计算出现小错误，你仍然能获得方法分和推理分。
4. Show Equations and Substitutions Clearly | 清晰呈现方程与代入
In IB mark schemes, method marks are often awarded for each visible step. Do not skip from the data directly to the final number.
在IB评分标准中，方法分通常按可见步骤给分。不要直接从已知数据跳到最终数字。
Always write the general equation before substituting values.
务必先写出一般方程，再代入数值。
For resistance in a wire, write:
对于导线电阻，应写成：
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