Gas pressure
Gas particles hit the walls of their container, and the many tiny hits make pressure. Pressure = force / area, in pascals (Pa).
Last updated
Analogy
Thousands of tiny balls bouncing against a drum.
Example
force = 600 Narea = 0.2 m2pressure = 600 / 0.2pressure = 3,000 Pa
In practice
Heating a closed gas makes the particles faster, so there are harder, more frequent hits and the pressure rises.
Practice
Flashcards
- What causes gas pressure?Particles hitting the walls of the container.
Questions people ask
Why does a gas's pressure rise when it is heated?
The particles gain energy and move faster. They hit the container walls harder and more often. Both effects increase the force on each square metre of wall. This is why a sealed aerosol can is dangerous in a hot car: pressure builds up inside.
Why does squeezing a gas increase its pressure?
In a smaller volume the same particles hit the walls more often, because they have less room to travel between hits. More hits each second means a larger force on the walls. At constant temperature, halving the volume of a gas doubles its pressure.