Definition
A gas law stating that, at a constant temperature, the volume of a confined gas varies inversely with the absolute pressure applied to it. In equation form: P1V1 = P2V2. As pressure increases, volume decreases proportionally; as pressure decreases, volume increases.
Plain English
If you squeeze a trapped gas harder, it takes up less space. If you let the pressure off, it expands. The hotter or cooler aspect is held still — only pressure and volume change.
Context Anchor
Seen in basic aircraft maintenance physics, especially when studying air pressure, gas-filled components, tires, and other sealed air spaces.
Derivation
Named after Robert Boyle, a 17th-century scientist who first described this relationship between pressure and volume. Knowing the law is named after the person who discovered it (rather than describing the effect) helps explain why the name itself gives no clue about what it does.
Why Pilots Care
Correct application prevents over- or under-pressurization of gas-filled components such as struts, tires, and fuel tanks when altitude changes.
Analogy
Think of a sealed syringe with the tip blocked. Push the plunger in and the trapped air gets harder to compress as its volume shrinks. Pull the plunger back and the same air spreads out into a larger space at lower pressure.
Grounding Statement
Boyle’s law is the simple idea that trapped gas pushes harder when it is squeezed into less space, as long as its temperature stays the same.
Intuition Check
Boyle’s law does not mean pressure always changes only because volume changes. It applies when the same gas is trapped and its temperature stays constant.
Example Sentence 1
Using Boyle's law, the technician calculated how much the volume of nitrogen in the strut would decrease when the system was pressurized to its service value.
Example Sentence 2
Before flight at high altitude, the crew confirmed that vent lines were clear so expanding gas in the fuel tanks would not over-pressurize per Boyle’s law.