Planar discrete system, moments and center of mass
Three circles are displayed, representing three masses in the plane. The area of the circle indicates its mass. You can move a mass by dragging the point at its center, and you can change the mass by dragging the point on its boundary.
As you play with the masses, see how the moments with respect to the -axis and -axis change. Observe how the center of mass changes as you change the masses.