📚 Year 7 CIE Physics: Unit Test Mock Paper Analysis | Year 7 CIE 物理：单元测试模拟卷解析
Mock papers are one of the best ways to prepare for your Year 7 CIE Physics unit test. In this article, we go through a typical mock paper question by question, breaking down key ideas, common mistakes, and top revision tips. Each section covers a major topic from the CIE Lower Secondary Physics curriculum, so you can see exactly how your understanding is tested.
模拟卷是准备 Year 7 CIE 物理单元测试的最佳方式之一。本文将对一份典型的模拟卷进行逐题解析，拆解核心概念、常见错误和重要的复习技巧。每个小节涵盖 CIE 初中物理课程的一个主要主题，帮助你直观地了解知识是如何被考查的。
1. Measuring Length and Time | 长度与时间的测量
15.3 cm, closer to 15.2 cm. She records the length as 15.2 cm. What is the uncertainty in this measurement, and how should the result be written? ding to the nearest 0.1 cm with an uncertainty of ±0.1 cm. The accepted way is 15.2 ± 0.1 cm, meaning the true length is between 15.1 cm and 15.3 cm. When using a stopwatch that reads to 0.01 s, a time of 8.57 s has an uncertainty of ±0.01 s. Always align your eye perpendicular to the scale to avoid parallax error.
模拟题：某学生用分度值为毫米的米尺测量铅笔长度，铅笔末端在15.2 cm和15.3 cm之间，更靠近15.2 cm，她记录为15.2 cm。问测量不确定度是多少？结果应如何书写？解析：最小分度值为1 mm = 0.1 cm，通常我们取读数至0.1 cm，不确定度常表示为±0.1 cm。规范记录为15.2 ± 0.1 cm，表示真值落在15.1 cm至15.3 cm之间。用可读0.01 s的秒表计时，若显示8.57 s，不确定度为±0.01 s。读数时视线必须垂直于刻度，避免视差。
2. Speed Calculations | 速度计算
time. In km/h: v = 36 km ÷ 1.5 h = 24 km/h. To convert to m/s, multiply by 1000/3600 or divide by 3.6: 24 km/h = 24 ÷ 3.6 = 6.67 m/s (or exactly 6 23 m/s). A distance–time graph for this journey would be a straight line with a constant positive slope if the speed is steady. Remember: speed is a scalar; velocity includes direction.
模拟题：一名骑行者用1.5小时骑了36 km。求平均速度，单位分别为km/h和m/s。解析：平均速度 = 总路程 ÷ 总时间。v = 36 km ÷ 1.5 h = 24 km/h。换算成m/s，除以3.6即可：24 km/h = 24 ÷ 3.6 ≈ 6.67 m/s。若速度恒定，这段运动的距离–时间图是一条斜率不变的斜直线。注意：速率是标量，速度则包含方向。
3. Mass, Weight and Gravity | 质量、重量与重力
gravitational field strength g = 10 N/kg. On the Moon, g = 1.6 N/kg. Calculate the toolbox' On the Moon: W = 12 kg × 1.6 N/kg = 19.2 N. The mass remains 12 kg everywhere, because mass is the amount of matter and does not depend on gravity. Many students confuse mass and weight – rams, weight in newtons. A spring balance measures weight; a beam balance compares masses.
模拟题：一名宇航员将12 kg的工具箱带到月球上。地球重力场强度g = 10 N/kg，月球上g = 1.6 N/kg。求工具箱在地球和月球上的重量，并对质量加以说明。解析：重量 = 质量 × 重力场强度（W = m × g）。地球上：W = 12 × 10 = 120 N，月球上：W = 12 × 1.6 = 19.2 N。质量始终是12 kg，因为质量是物体所含物质的多少，与重力无关。很多学生会混淆质量与重量——质量以千克为单位，重量以牛顿为单位。弹簧秤测重量，杆秤测质量。
4. Density | 密度
y of water = 1.0 g/cm³). Answer: Density ρ = mass ÷ volume. ρ = 540 g ÷ 200 cm³ = 2.7 g/cm³. To convert to kg/m³, multiply by 1000: 2.7 g/cm³ = 2700 kg/m³. Since 2.7 g/cm³ > 1.0 g/cm³, the block sinks. Common pitfall: using inconsistent units – nd volume units. Use ρ = m / V and the triangle method to rearrange: m = ρ × V, V = m ÷ ρ.
模拟题：一块金属的质量为540 g，体积为200 cm³。求其密度，单位分别为g/cm³和kg/m³，并判断它在水中浮沉（水的密度ρ = 1.0 g/cm³）。解析：密度ρ = 质量 ÷ 体积。ρ = 540 g ÷ 200 cm³ = 2.7 g/cm³。换算成kg/m³，乘以1000：2.7 g/cm³ = 2700 kg/m³。因为2.7 > 1.0，所以金属下沉。常见错误：单位不统一——必须确保质量和体积的单位对应。利用公式ρ = m ÷ V 和三角转换法：m = ρ × V，V = m ÷ ρ。
5. States of Matter and Changes of State | 物态与物态变化
Mock question: The graph shows the temperature of a pure solid being heated at a steady rate. There are two flat sections: one at 0 °C and one at 100 °C. Explain what is happening at these temperatures. Answer: The first flat section at 0 °C represents melting (solid to liquid). Heat energy is absorbed to break the forces between particles, so the temperature stays constant until all the solid has melted. The second flat section at 100 °C represents boiling (liquid to gas). Again, energy is used to separate particles completely, not to raise the temperature. In the solid state, particles are closely packed in a fixed pattern; in the liquid they can slide past each other; in the gas they move freely in all directions.
模拟题：某纯物质受热均匀，温度–时间图像出现两个平台：一个在0 °C，另一个在100 °C。请解释这两个温度段发生了什么。解析：0 °C平台对应熔化（固态→液态）。热量用于克服粒子间的束缚，因此温度保持不变，直到所有固体熔化。100 °C平台对应沸腾（液态→气态）。能量再次被用来将粒子完全分开，而非升温。固态时粒子紧密排列，位置固定；液态时粒子可相互滑动；气态时粒子自由向四面八方运动。
6. Series Circuits | 串联电路
p 2, and explain the current in the circuit. Answer: In a series circuit, the supply voltage is shared between components. Since the lamps are identical, they share the voltage equally: each should receive about 3.0 V. The reading 2.9 V is close to this ideal value. Thus the voltmeter across lamp 2 will also read approximately 2.9 V, and the sum (2.9 V + 2.9 V = 5.8 V) should roughly equal the battery voltage of 6.0 V within experimental error. The current is the same at every point in a series circuit. If you placed an ammeter at different positions, all readings would be identical. A break anywhere in the circuit stops the current in the whole loop.
模拟题：两盏相同灯泡串联在6.0 V电池上。灯泡1两端电压表读数为2.9 V。预测灯泡2两端的电压，并解释电路中的电流情况。解析：在串联电路中，电源电压分配给各用电器。因为灯泡相同，它们平分电压：理想上各分得3.0 V，实测2.9 V很接近。故灯泡2两端电压也约为2.9 V，两者之和（5.8 V）在误差范围内接近电池电压6.0 V。串联电路中各处电流相等。将电流表接在不同位置，读数完全相同。电路中任何一处断开，整个回路的电流都会跟着停止。
7. Magnetic Poles | 磁极
Mock question: You are given two unmarked bar magnets. How could you identify the north and south poles? Draw the magnetic field pattern when two north poles are brought close together. Answer: To find poles, suspend one magnet freely with a thread. The end that points to Earth's geographic North is the north-seeking pole (N). Alternatively, bring a known magnet close: like poles repel, unlike poles attract. When two north poles face each other, the field lines curve away from each other, showing repulsion. Magnetic field lines emerge from the north pole and go to the south pole. They never cross. The Earth itself has a magnetic field; its south magnetic pole is near the geographic North Pole, which is why a compass needle's north pole points north.
模拟题：给你两根无标记条形磁铁，如何辨别南北极？画出两个北极相对时的磁场分布图。解析：辨别磁极可用细线悬吊一根磁铁，指北的一端即为指北极（N）；或用已知磁极靠近：同极相斥，异极相吸。两个北极相对时，磁感线互相排斥弯曲，显示出排斥力。磁感线从北极出发，进入南极，且永不相交。地球本身具有磁场，地磁南极靠近地理北极，因此指南针的北极指向北方。
8. Sound Propagation | 声音的传播
Mock question: An electric bell is placed inside a sealed glass jar. When the air is pumped out, the sound becomes fainter until it disappears. Explain this observation. Why can astronauts on the Moon not hear each other directly? Answer: Sound is a mechanical wave that requires a medium (solid, liquid or gas) to travel. In a vacuum, there are no particles to vibrate, so sound cannot propagate. When air is removed from the jar, the bell's sound waves have no medium and we cannot hear them. On the Moon there is no atmosphere (almost a vacuum), so direct speech cannot travel; astronauts use radio waves, which are electromagnetic and can move through a vacuum. Sound generally travels fastest in solids, slower in liquids, and slowest in gases, because particles are closest in solids and can pass vibrations more quickly.
模拟题：将一个电铃放入密封瓶，抽走空气后，铃声逐渐减弱直至消失。请解释这一现象，并说明月球上的宇航员为何不能直接对话。解析：声音是一种机械波，需要介质（固、液、气）才能传播。真空中没有振动的粒子，声波无法传递。瓶内空气被抽走后，声波的介质消失，因此听不到铃声。月球上几乎没有大气（近乎真空），说话声无法直接传播；宇航员利用能在真空中传播的电磁波——无线电来通信。通常声音在固体中传播最快，液体次之，气体最慢，因为固体粒子排列最紧密，振动传递更迅速。
9. Light Reflection | 光的反射
ce and the angle of reflection. Draw a labelled ray diagram. Answer: The angle of incidence i is measured between the incident ray and the normal (a line perpendicular to the mirror). Since the ray makes 25° with the mirror, i = 90° – ls the normal, incident ray, reflected ray, i and r. This question often appears with a periscope or mirror alignment task.
模拟题：一束光线射向平面镜，入射光线与镜面夹角为25°。求入射角和反射角，并画出标有角度的光路图。解析：入射角i是入射光线与法线（垂直于镜面的线）的夹角。光线与镜面夹角25°，所以i = 90° – 25° = 65°。根据反射定律，反射角r = 入射角i，故r = 65°。入射光线、反射光线和法线在同一平面内。规范的光路图需标出法线、入射光线、反射光线及i、r。此类题也常结合潜望镜或镜面调整情境出现。
10. The Solar System and Data Analysis | 太阳系与数据分析
Mock question: The table gives the mean distance from the Sun and the orbital period for three planets: Earth (150 million km, 1.0 year), Mars (228 million km, 1.9 years), and Jupiter (779 million km, 11.9 years). Describe the relationship between distance and period. Use it to predict whether Saturn, at 1434 million km, would have a period longer or shorter than Jupiter's. Answer: The further a planet is from the Sun, the longer its orbital period (year). This is because the gravitational pull from the Sun is weaker at greater distances, so the planet moves more slowly and has a larger circumference to travel. Based on the trend, Saturn, being much farther than Jupiter, will have a period even longer than 11.9 years (actual ~29.5 years). This concept links to Kepler's laws. Graph guidelines: when plotting distance vs period, you will see a curved trend – not a straight line. Always label axes and include the unit (e.g., distance in millions of km, period in years).
模拟题：下表给出三颗行星到太阳的平均距离和公转周期：地球（1.5 × 10⁸ km，1.0年），火星（2.28 × 10⁸ km，1.9年），木星（7.79 × 10⁸ km，11.9年）。描述距离与周期的关系，并预测距太阳1.434 × 10⁹ km的土星的公转周期比木星长还是短。解析：行星离太阳越远，公转周期（年）越长。这是因为距离越远，太阳引力越弱，行星运行更慢且轨道周长更大。根据趋势，土星比木星远得多，其周期将远大于11.9年（实际约29.5年）。这一定性与开普勒定律相联系。画图时，距离–周期图呈曲线趋势，不是直线。必须标注坐标轴和单位（如距离单位百万公里，周期单位年）。
Published by TutorHao | Physics Revision Series | aleveler.com
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