Center of Mass Playground

The Center of Mass

The Center of Mass is the unique point where the weighted average of all mass in a system is located. You can think of it as the system's "balance point." A system's motion can be described by the motion of its center of mass, which moves as if all the system's mass was concentrated there.

Internal vs. External Forces

• The most important rule: The motion of the center of mass is only affected by external forces (like gravity).
• Internal forces (like particles colliding, or an explosion pushing them apart) will not change the motion of the center of mass at all.
• Press "Explode!" to see this in action! The particles will fly apart, but the red 'X' will not move.