Thermal physics
Structure of matter and kinetic theory
Watch the random thermal motion of gas molecules in a closed vessel and how wall collisions produce pressure. Check qualitatively that mean kinetic energy tracks temperature, , and .
Equipment
- Virtual closed vessel holding randomly moving molecule dots
- Temperature slider controlling the molecules' characteristic speed
- Slider for the number of molecules N in the vessel
- Vessel walls and a collision/pressure readout
Procedure
Observe thermal motion
Run the simulation at moderate temperature and follow a single molecule: its path is jagged, redirecting at each collision with another molecule or the wall. Every wall hit transfers momentum — averaged, these impulses produce pressure.
Raise the temperature
Drag the temperature slider up and observe: molecules move faster, and wall collisions become more frequent and harder. Since the characteristic speed scales as , mean kinetic energy is proportional to T — consistent with .
Change the molecule count
Hold T fixed and increase N: the density of wall impacts rises proportionally, so pressure grows as . Predict the pressure when N doubles at fixed V, T, then compare with the picture.