📚 Year 10 CIE Physics: Common Misconceptions and How to Correct Them | 10年级CIE物理：常见误区与纠正方法
In IGCSE Physics, many students develop ideas that seem logical but are scientifically incorrect. These misconceptions can block true understanding and lead to mistakes in exams. This article highlights ten of the most common misconceptions among Year 10 learners and provides clear, exam-focused corrections to help you build a solid foundation in physics.
在IGCSE物理学习中，许多学生会产生一些看似合理但科学上错误的观念。这些误区会阻碍真正的理解，并在考试中导致失分。本文列出10年级学生最常见的十大误区，并提供清晰的、符合考试要求的纠正方法，帮助你打下扎实的物理基础。
1. Mass vs. Weight | 质量与重量
A very common student statement is 'Mass and weight are the same thing.' In everyday language, we ask 'What is your weight in kilograms?' which reinforces the confusion. In physics, mass is the measure of the amount of matter in an object, measured in kilograms (kg). It is a scalar quantity and does not change with location. Weight is the gravitational force acting on that mass, measured in newtons (N). Weight depends on the gravitational field strength g, which on Earth is about 10 N/kg. The relationship is:
一个非常普遍的学生说法是“质量和重量是一回事”。日常用语中我们经常问“你的体重多少公斤？”，这加深了混淆。在物理学中，质量是物体所含物质的量，单位是千克 (kg)。它是标量，不随位置改变。重量是作用在该质量上的重力，单位是牛顿 (N)。重量取决于重力场强度 g，在地球上约为 10 N/kg。关系式为：
weight = mass × gravitational field strength → W = m g
e Moon, g is about 1.6 N/kg, so their mass is still 50 kg but weight becomes only 80 N. Always check units: mass in kg, weight in N. A good trick: if the question asks for 'weight' and the answer is in kg, something is wrong.
因此，如果一名学生质量为 50 kg，他在地球上的重量为 50 × 10 = 500 N。在月球上，g 约 1.6 N/kg，所以他的质量仍为 50 kg，但重量仅为 80 N。务必检查单位：质量用 kg，重量用 N。一个小技巧：如果题目问“重量”而答案以 kg 给出，那一定是错的。
2. Speed vs. Velocity | 速率与速度
Many learners use 'speed' and 'velocity' interchangeably. However, speed is a scalar quantity that only measures how fast an object is moving (magnitude). Velocity is a vector: it includes both speed and direction. This distinction is essential in topics like motion, forces, and circular motion. For example, a car travelling around a roundabout at a constant speed of 30 km/h has a constantly changing velocity because its direction changes. Any change in velocity means there is acceleration, even if the speed stays the same.
许多学生将“速率”和“速度”混用。然而，速率是标量，仅描述物体运动有多快（大小）。速度是矢量，同时包含速率和方向。这一区别在运动、力和圆周运动等课题中至关重要。例如，一辆汽车以 30 km/h 的恒定速率绕环岛行驶，其速度时刻在变，因为方向在不断改变。速度的任何变化都意味着存在加速度，即使速率不变也是如此。
city, we consider displacement (shortest distance in a given direction) over time. If you run once around a 400 m track and finish where you started, your average speed is (400 m / time), but your average velocity is zero because displacement is zero.
平均速率的公式为：速率 = 距离 ÷ 时间 (v = s / t)。对于速度，我们考虑位移（在给定方向上的最短距离）除以时间。如果你绕 400 米跑道跑一圈并回到起点，平均速率是 (400 m / 时间)，但平均速度为零，因为位移为零。
3. Acceleration Always Means Speeding Up | 加速度总是加速
Students often believe that acceleration only means getting faster. In physics, acceleration is the rate of change of velocity. If an object slows down, we call it deceleration or negative acceleration. If the velocity changes direction, there is acceleration even if speed is constant (as in circular motion). Constant acceleration does not mean constant velocity; it means velocity changes by the same amount each second. For example, a falling object in free fall has an acceleration of about 10 m/s² near Earth's surface, meaning its velocity increases by 10 m/s every second downward.
学生常认为加速度就是指速度变快。在物理学中，加速度是速度的变化率。如果物体减速，我们称之为负加速度或减速度。如果速度方向改变，即使速率不变（如圆周运动），也存在加速度。恒定加速度并不意味着恒定速度；它意味着速度每秒钟变化相同的量。例如，自由落体在地球表面附近的加速度约为 10 m/s²，意味着其向下速度每秒增加 10 m/s。
(v - u) / t, where v is final velocity, u is initial velocity, and t is time. If v is smaller than u, a is negative. Always remember: an object can have a constant speed but be accelerating if it's changing direction. This is why satellites stay in orbit.
加速度的公式为：a = (v - u) / t，其中 v 为末速度，u 为初速度，t 为时间。如果 v 小于 u，a 为负值。记住：物体可以有恒定速率但同时有加速度，只要它在改变方向。这就是
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