A group of particles is launched with the same
speed inside a container. Once the particles collide with the walls of the
container the speeds become randomized and the simulation represents the
random motion of gas molecules contained a box.
The histogram graph on the right shows the number of molecules (on the vertical axis) which have a given speed (on the horizontal axis).
What is the initial speed given to the group of particles? Click on the button below to restart the molecules and show the instantaneous speeds:
You will notice that the instantaneous speeds looks rather random. Pause the simulation after one minute and make a table of the number of molecules and the speeds for each of the bars in the histogram (holding the mouse down in the graph at the top center of each bar gives the values). Run the simulation for another minute and make a second table of number of molecules and speeds. Do you see any patter here?
If the speeds are averaged over many seconds, however, a pattern emerges. Click on the button below to restart the molecules and show the average speeds. Click 'Clear Graph' after the simulation has started and wait a minute or two to see how what pattern emerges. Make a sketch of the distribution. This is the Maxwell-Boltzman speed distribution.
Is the distribution symmetric? Why would you expect the distribution to not be symmetric? (Hint: Think about the theoretical maximum and minimum speeds.)
Restart the 'Average Speed' simulation, clear the graph and then let it run for two minutes before clicking on 'pause' to stop the simulation. Make a table of the average number of molecules and the average speed for each of the bars in the histogram. What is the most probably speed (the speed which the largest number of molecules have, on average)? Is the most probable speed (given by the peak in the distribution) the same as the initial speed?