Acceleration Caused by Gravity | 重力加速度

📚 Acceleration Caused by Gravity | 重力加速度

In CIE A-Level Physics, the acceleration caused by gravity, denoted by g, is a fundamental idea linking force, motion, and gravitational fields. This article explains its meaning, measurement, use in kinematics, and common exam pitfalls.

在 CIE A-Level 物理中，重力加速度 g 是联系力、运动和引力场的基本概念。本文解释其含义、测量方法、在运动学中的应用以及常见考试误区。

1. What is Acceleration due to Gravity? | 什么是重力加速度？

Acceleration due to gravity is the acceleration experienced by a body when the only force acting on it is gravity. Near Earth’s surface its magnitude is about 9.81 m s⁻² and its direction is vertically downward.

重力加速度是物体仅在重力作用下所获得的加速度。在地球表面附近其大小约为 9.81 m s⁻²，方向竖直向下。

Because g is an acceleration, its SI unit is m s⁻². In the absence of air resistance, all objects fall with the same acceleration g, regardless of their mass.

由于 g 是加速度，其 SI 单位是 m s⁻²。在没有空气阻力时，所有物体无论质量大小都以相同的加速度 g 下落。

In CIE numerical problems, g is usually taken as 9.81 m s⁻² unless the question gives a different value. It is a vector quantity, so its direction must be shown clearly in calculations.

在 CIE 数值题中，除非题目给出不同值，通常将 g 取为 9.81 m s⁻²。它是矢量，因此计算中必须清楚标明方向。

2. Gravitational Field Strength and g | 引力场强度与 g

In CIE A-Level Physics, g can also be described as the gravitational field strength, defined as the gravitational force per unit mass on a small test mass.

在 CIE A-Level 物理中，g 也可描述为引力场强度，定义为作用在小检验质量上每单位质量的引力。

g = F/m

This gives g the equivalent unit N kg⁻¹. Since 1 N = 1 kg m s⁻², the units N kg⁻¹ and m s⁻² are identical.

这使 g 具有

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