📚 KS3 CIE Conservation of Energy Worksheet Mark Scheme | KS3 CIE 能量守恒作业评分标准
This mark scheme is designed to accompany a KS3 CIE science worksheet on conservation of energy. It clarifies what examiners expect for each question, how marks are awarded, and where learners commonly lose marks. Use it for self-assessment or classroom feedback.
本评分标准配套 KS3 CIE 科学中关于能量守恒的作业使用。它说明考官对每道题的期望、如何给分以及学生常见失分点。可用于自评或课堂反馈。
1. How to Use This Mark Scheme | 如何使用本评分标准
Read the model answer first, then compare it with your own response. Marks are often given for stating energy stores, describing transfers in the correct direction, and using key scientific terms such as 'conservation' and 'dissipated'. In calculation questions, one mark is usually for substitution, one for rearrangement, and one for the final answer with a unit.
先阅读模型答案，再与自己的作答进行对比。分数通常给在说出能量储存、按正确方向描述能量转移，以及使用 '守恒' '耗散' 等关键科学术语上。在计算题中，通常代入数据得一分，公式变形得一分，带单位的最终答案得一分。
2. Core Principle: Energy Cannot Be Created or Destroyed | 核心原理：能量不能被创造或消灭
The conservation of energy states that energy cannot be created or destroyed; it can only be transferred from one store to another or from one object to another. A common one-mark answer is: 'Energy is conserved.' A two-mark answer requires you to add: 'because it is only transferred between stores, not used up.' Avoid saying energy is 'lost' unless you explain it is dissipated to the surroundings as thermal energy.
能量守恒定律指出，能量不能被创造或消灭，只能从一个储存转移到另一个储存，或从一个物体转移到另一个物体。常见的一分答案是：'能量是守恒的。' 两分答案需要补充：'因为能量只是在储存之间转移，没有被用掉。' 除非解释为能量以热能形式耗散到周围环境中，否则避免说能量 '丢失'。
3. Identifying Energy Stores | 识别能量储存
At KS3, learners should recognise eight energy stores: kinetic, chemical, gravitational potential, elastic potential, thermal, nuclear, magnetic and electrostatic. A typical worksheet question shows a moving car. Acceptable answers include: 'kinetic energy' for movement, 'chemical energy' in fuel, and 'thermal energy' in hot brakes or engine.
在 KS3 阶段，学生需要识别八种能量储存：动能、化学能、重力势能、弹性势能、热能、核能、磁能和静电能。作业中的典型题目会展示一辆行驶的汽车。可接受的答案包括：运动对应 '动能'，燃料中对应 '化学能'，热的刹车或发动机对应 '热能'。
| Store / 能量储存 | Description / 描述 | Example / 例子 | Typical mark / 典型分值 |
|---|---|---|---|
| Kinetic / 动能 | Energy of movement / 运动的能量 | A moving car / 行驶的汽车 | 1 |
| Chemical / 化学能 | Stored in fuels, food, batteries / 储存在燃料、食物、电池中 | Petrol in a car / 汽车中的汽油 | 1 |
| Gravitational potential / 重力势能 | Stored due to height / 因高度而储存 | A book on a shelf / 书架上的书 | 1 |
| Elastic potential / 弹性势能 | Stored in stretched or compressed objects / 储存在拉伸或压缩的物体中 | A stretched spring / 拉伸的弹簧 | 1 |
| Thermal / 热能 | Stored in hot objects / 储存在热物体中 | Hot brakes / 热的刹车 | 1 |
| Nuclear / 核能 | Stored in atomic nuclei / 储存在原子核中 | Uranium fuel / 铀燃料 | 1 |
| Magnetic / 磁能 | Stored in magnets / 储存在磁体中 | Two attracting magnets / 相互吸引的磁铁 | 1 |
| Electrostatic / 静电能 | Stored in separated charges / 储存在分离的电荷中 | A charged balloon / 带电的气球 | 1 |
4. Marking Energy Transfer Statements | 能量转移陈述评分
Questions often ask you to describe the energy transfer in a device such as a battery-powered torch. A model three-mark answer is: 'Chemical energy in the battery is transferred electrically to the lamp, then to the surroundings as light and thermal energy.' Marks are awarded as follows: 1 mark for the chemical store, 1 mark for the electrical transfer, and 1 mark for useful light plus wasted thermal. Reversing the direction or omitting the wasted store loses a mark.
题目经常要求描述设备中的能量转移，例如电池供电的手电筒。三分模型答案：'电池中的化学能通过电流传递到灯泡，然后以光能和热能的形式传递到周围环境。' 给分如下：化学储存得一分，电转移得一分，有用的光能加浪费的热能得一分。方向写反或遗漏浪费的储存会扣一分。
5. Common One-Mark Questions | 常见一分题
The list below shows frequent one-mark items and accepted answers. Each answer must use the correct scientific term to receive the mark.
下方列表展示了常见的一分题和可接受答案。每个答案必须使用正确的科学术语才能得分。
- State the principle of conservation of energy. Answer: Energy cannot be created or destroyed. — 说出能量守恒定律。答案：能量不能被创造或消灭。
- Name one wasted energy store in a light bulb. Answer: Thermal energy. — 说出灯泡中一种浪费的能量储存。答案：热能。
- What happens to the total energy in a closed system? Answer: It stays the same. — 封闭系统中的总能量会怎样？答案：保持不变。
- Give one example of an energy transfer. Answer: Chemical energy to kinetic energy in a running child. — 举一个能量转移的例子。答案：跑步儿童体内化学能转化为动能。
6. Calculations: Kinetic and Gravitational Potential Energy | 计算：动能和重力势能
Some KS3 CIE worksheets include simple calculations using kinetic energy and gravitational potential energy. Marks are awarded for writing the correct equation, substituting values with units, and giving the answer with the unit joule (J). The equations are shown below.
一些 KS3 CIE 作业包含使用动能和重力势能的简单计算。给分点包括写出正确公式、代入带单位的数值、以及给出带单位焦耳 (J) 的答案。公式如下所示。
KE = ½ m v² | GPE = m g h | Efficiency = (useful output ÷ total input) × 100%
aised 2 m on Earth (g = 10 N/kg) gives GPE = 0.5 × 10 × 2 = 10 J. Always include the unit.
示例：计算质量为 2 kg、速度为 3 m/s 的小球的动能。代入：KE = ½ × 2 × 3² = 9 J。常见错误是将质量平方而不是速度平方。对于重力势能，一个 0.5 kg 的物体被举高 2 m（地球 g = 10 N/kg），GPE = 0.5 × 10 × 2 = 10 J。始终要包含单位。
7. Efficiency and Wasted Energy | 效率与浪费的能量
Efficiency is calculated as useful output energy divided by total input energy, multiplied by 100%. It is always less than or equal to 100% because some energy is always dissipated as thermal energy to the surroundings. A two-mark efficiency
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