Motion, temperature and pressure
Predict firstWhen a particle hits a stationary wall, which component of its velocity reverses?
Connect temperature, particle motion, momentum transfer at the wall, and pressure.
Prerequisites: Pressure is the average force per unit area; momentum depends on mass and velocity.Follow one particle first
Predict firstWhen a particle hits a stationary wall, which component of its velocity reverses?
The red particle is one chosen sample. It travels in a straight line between wall collisions; an elastic reflection reverses only the velocity component perpendicular to the wall, so the speed stays the same. Turn on the trail and press play.
How to observe
- Follow one particle and watch its elastic collisions with the walls
- Raise the absolute temperature and compare the motion of the whole group of particles
- Explain pressure through momentum transfer
Model notes
A sketch of an ideal gas with 96 equal-mass point particles. Velocity components are sampled from a normal distribution and changing the temperature rescales them by √T; the spheres are drawn enlarged. Only elastic reflection from stationary walls is computed, collisions between particles are omitted, and real heating or the approach to thermal equilibrium is not simulated. The readouts are theoretical ratios, not a pressure measured from finite collisions.