Ch.1 · Unit 2

Temperature — what is actually moving

Drag the temperature control. Every scene below reacts to the same number — because they're all the same thing underneath.

25 °C298 K
0 K
absolute zero
273 K
ice melts
373 K
water boils
The shaking has stopped completely. Nothing is moving. Real gases would freeze solid long before this point — but the idea is exactly right.
PARTICLES
ROOM
TEA
SUGAR
BALLOON
A box of molecules
This is what temperature actually is: how fast these are moving, on average.
avg speed
— m/s
Smell crossing a room
Perfume molecules drift outward. They genuinely fly — faster when it's warm.
🧴
reaches far wall in
— s
Hot tea steams. Cold tea doesn't.
Steam is just the fastest molecules escaping the surface entirely.
~~~
🍵
Sugar dissolves faster in hot water
More collisions, and harder ones, at the same slider position you've been dragging.
🥛
🧊
DROP THE CUBE
A balloon shrinks in the fridge
Slower molecules hit the inside wall weaker and less often — so the wall isn't pushed out as far.
🎈
Predict → Warm It → Compare
Cold morning, hot afternoon
Your tyre reads 2.20 bar at 25 °C, first thing in the morning. By afternoon the tarmac has heated the same sealed air to 50 °C — same tyre, same volume, same amount of air. Drag the puck to guess the new gauge reading, then warm it up.
25 °C → 50 °C
🛞
Drag to predict: gauge reading at 50 °C
2.00 bar3.00 bar
WARM IT UP →