AS Physics Unit 1 Mark Scheme Jan 2022: Formula Derivation | AS物理第一单元2022年1月评分方案：公式推导

📚 AS Physics Unit 1 Mark Scheme Jan 2022: Formula Derivation | AS物理第一单元2022年1月评分方案：公式推导

The Edexcel AS Physics Unit 1 exam in January 2022 tested students’ ability to derive fundamental equations from first principles. The mark scheme reveals exactly how examiners award marks for clear logical steps, correct algebraic manipulation, and proper use of definitions. This article breaks down the key derivations expected in that exam and explains the marking requirements, helping you secure full marks in derivation questions.

2022年1月的Edexcel AS物理第1单元考试考查了学生从基本原理推导基本方程的能力。评分方案揭示了考官如何根据清晰的逻辑步骤、正确的代数运算以及准确定义来给分。本文详细解析该考试中涉及的典型推导，并解释评分要求，帮助你在推导题中获得满分。

1. Understanding the Mark Scheme Requirements | 理解评分方案要求

The mark scheme for derivation questions typically allocates ‘M’ marks for method, ‘A’ marks for accuracy, and sometimes ‘B’ marks for stating key relationships or assumptions. For a perfect answer, you must show all intermediate steps, state any assumptions (such as constant acceleration or absence of external forces), and include the final formula in its standard form.

推导题的评分方案通常将分数分为“方法分”（M分）、“准确度分”（A分），有时还有用于陈述关键关系或假设的“基本分”（B分）。要获得满分，你必须展示所有中间步骤，陈述任何假设（例如匀加速度或没有外力），并将最终公式表达为标准形式。

Examiners will look for the use of fundamental definitions, such as a = (v-u)/t or average velocity = (u+v)/2, as the starting point. Missing a logical step or skipping algebraic manipulation can cause you to lose marks even if the final answer is correct.

考官会寻找基本定义作为起点，例如 a = (v-u)/t 或平均速度 = (u+v)/2。一旦缺少逻辑步骤或跳过代数推导，即使最终答案正确也可能丢分。

2. Foundations: Definitions and Assumptions | 基础：定义和假设

Before any derivation, it is essential to state the definitions and assumptions you will use. For uniformly accelerated motion, acceleration is constant: a = constant. The definition of acceleration is a = (v-u)/t, where v is final velocity, u is initial velocity, and t is time.

在进行任何推导之前，务必先陈述你将使用的定义和假设。对于匀加速直线运动，加速度为常数：a = 常量。加速度的定义为 a = (v-u)/t，其中 v 是末速度，u 是初速度，t 是时间。

Displacement s or x is the area under a velocity-time graph. This geometric interpretation is often the quickest route to the kinematic equations. The assumption of constant acceleration means the v-t graph is a straight line.

位移 s 或 x 是速度-时间图下方的面积。这一几何解释通常是推导运动学方程的最快捷途径。匀加速假设意味着 v-t 图是一条直线。

For dynamics derivations, Newton’s second law F = ma and the definition of work W = Fs cosθ (with θ = 0 for motion in a straight line) are the foundation. It is assumed that mass remains constant.

对于动力学推导，牛顿第二定律 F = ma 以及功的定义 W = Fs cosθ（在直线运动中 θ = 0）是基础。假设质量保持不变。

3. Deriving Displacement–Time Equation x = ut + ½at² | 推导位移-时间方程 x = ut + ½at²

This derivation is a classic AS Physics question. Start by sketching

Published by TutorHao | Physics Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）