Gas Basics: Particles in Motion
A gas is a collection of tiny particles, atoms or molecules, moving randomly in all directions.
They bounce off each other and off the walls of their container. Between collisions, they travel in straight lines.
Watch the particles on the right. Notice how they spread out to fill the entire box.
The graph on the right shows the pressure on the walls. Every time a particle bounces off a wall, it pushes on it. The combined effect of countless tiny pushes is what we call pressure.
Try adding more particles with the create tool and watch what happens to the pressure.
More particles → more wall collisions → higher pressure.
Alternatively, you can increase pressure by injecting energy. Try Resetting the simulation, then use the move tool to grab a particle and throw it around very fast.
By moving the particle faster, you increase its momentum, leading to more forceful collisions with the walls.
This is the fundamental insight: macroscopic properties like pressure emerge from the collective behavior of many tiny particles. The ideal gas law captures this relationship mathematically.
Note: Because these simulations use time-averaged smoothing, changes in pressure are gradual. You may need to add a lot of particles to see a significant move on the graph. You can always hit Reset to clear the box and compare the baseline!