Pressure is the force per area acting on a surface.
This simulation shows a container of particles on the left and the
instantaneous pressure in the container due to the particles colliding
with the walls as a function of time in the graph on the right.
The table underneath calculates the pressure three ways:
a) from the ideal gas law; P = NkT/V where Boltzmann's constant, k, is
set to 1 b) from the momentum change of the particles hitting the walls;
P = dp/dt and c) the average pressure; ‹P> over 100 time steps.