📚 Pressure in a Balloon | 气球里的压强
When you blow up a balloon, the rubber stretches and the air inside pushes outward. Why does this happen? The answer lies in pressure, particle motion, and forces. This article explains the key KS3 CIE ideas about pressure in a balloon, using simple experiments and examples.
当你吹气球时，橡胶被拉伸，里面的空气向外推。为什么会这样？答案在于压强、粒子运动和力。本文用简单的实验和例子解释 KS3 CIE 中关于气球内压强的关键概念。
1. What Is Pressure? | 什么是压强？
Pressure is a measure of how much force is spread over a certain area. A large force on a small area gives a high pressure. The formula is:
压强是衡量力在一定面积上分散程度的量。大的力作用在小的面积上会产生高压强。公式为：
P = F ÷ A
In this equation, P stands for pressure in pascals (Pa), F stands for force in newtons (N), and A stands for area in square metres (m²).
在这个公式中，P 代表压强，单位是帕斯卡（Pa）；F 代表力，单位是牛顿（N）；A 代表面积，单位是平方米（m²）。
One pascal is equal to one newton per square metre, written as 1 Pa = 1 N m⁻².
一帕斯卡等于每平方米一牛顿，写作 1 Pa = 1 N m⁻²。
2. Particles Inside a Balloon | 气球内的粒子
Air is made of tiny particles, mainly nitrogen and oxygen molecules, that are constantly moving in all directions. Inside a balloon, these particles collide with the inner rubber surface.
空气由微小的粒子（主要是氮分子和氧分子）组成，它们不断地向各个方向运动。在气球内部，这些粒子与橡胶内壁发生碰撞。
Each collision gives the wall a tiny push, called a force. Billions of collisions every second produce a steady outward push on the balloon.
每次碰撞都给气球壁一个微小的推力，称为力。每秒数十亿次碰撞对气球产生稳定的向外推力。
Because pressure is force divided by area, the total force of all these collisions spread over the inside surface gives the gas pressure.
由于压强等于力除以面积，所有这些碰撞的总力分散在内部表面上，就产生了气体压强。
3. How a Balloon Creates Pressure | 气球如何产生压强
Before you blow into a balloon, the rubber is limp and
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