Kinetic Gas Theory
Box of bouncing molecules. Builds on Conservation of Momentum.
A sealed box contains 1000 air molecules at room temperature (300 K). You double the temperature to 600 K.
What happens to the average speed of the molecules?
Speed goes up by √2 ≈ 41%, not double! Temperature relates to kinetic energy (v²), not velocity (v).
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Watch the molecules bounce. Raise the temperature — they speed up. Watch how the pressure (wall hits) increases.
½mv² = (3/2)kT
Temperature IS molecular motion. Hot = fast molecules. Cold = slow molecules.
Heat makes air molecules move faster → higher pressure → balloon expands (or pops!)
Mercury or alcohol expands because heat makes molecules push apart — measuring temperature through expansion
Sound travels faster in hot air because molecules are moving faster — message carriers move quicker
“Temperature is not a thing — it's a measure of how fast atoms jiggle.”
Gas Simulator
Control a box of molecules. Adjust temperature and volume to see pressure change in real time.
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Set temperature to minimum and watch the molecules barely move. Now crank it to maximum — see them ricochet like pinballs! Count wall hits per second — that's pressure.
The ideal gas law PV = NkT emerges naturally from billions of tiny elastic collisions. Thermodynamics is just statistics applied to bouncing balls.