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http://webphysics.davidson.edu/Applets/TaiwanUniv/collision1D/collision1D.html

Here you will find a java applet that simulates collisions.
There are several variables you can change:
MASS: change the mass of either object by right or left clicking on the mass while the applet is paused.
VELOCITY: click and drag the yellow arrow for either mass while the applet is paused.
RESTITUTION COEFFICIENT: this value describes how "elastic" the collision is.  set at one, all of the kinetic energy is conserved; set at zero and the masses stick together.
FRAME OF REFERENCE: there are four to choose from

  • the lab; this is how we are used to seeing things (with us standing still)
  • mass1 or mass 2; see how it looks from the ball's point of view (so the ball stays still)
  • the center of mass; you see things move in relation to the center of mass (is stays stationary)


    • EXPERIMENT 1: Click reset. Aim the velocities at each other and set them to 30 (one will be negative).  Click start. Describe the motion of the center of mass (the "X")

    EXPERIMENT 2: Click reset. Aim the velocities at each other and set them to 30.  Change the Restitution Coefficient to zero and click start.  What happens?
    Describe the motion of the center of mass.

    EXPERIMENT 3: Click reset.  Set the velocity of one of the masses to zero.  Click start.  What happens upon collision?  What is the speed of the hit ball?  What is the speed of the previously moving ball?  How does the speed of the "X" relate to the speed of the moving ball?

    EXPERIMENT 4: Click reset.  Set the restitution coefficient to zero.  Click start.  What happens to the velocity of the "X" after the collision?

    EXPERIMENT 5: Click reset.  Change the mass of one of the balls.  What happens to the center of mass (the "X") as you change the mass?

    EXPERIMENT 6: Click reset.  Change the frame of reference to "m1". Make both of the masses the same.  Set the restitution coefficient to "1". Click start.  NOTE: It is very hard for people to understand how others see the world!  Now you see things as mass1 would see them.   Describe what you see.