Brownian motion

Applet by Fu-Kwun Hwang


  • Each circle represents a gas molecule.
  • N is the total number of molecules in the area.
  • Enter a value into the text field and press RETURN.
  • m2/m1 is the mass ratio of the red ball to the gray ball (try it, and find out the difference).
  • Press + for faster motion.
  • Press - for slower motion.
  • Click the 'trace' checkbox to show the trace for one of the molecules (red).
  • Click it again to turn it off and clear the screen.
  • Right Click to stop the animation, click it again to resume.
  • While the animation is stopped, drag the red ball to relocate its position.
  • If you click the No boundary checkbox, particles moving to the right edge will appear at the left edge again instead of colliding with the wall.