Conservation of Energy:
When Euler's Disk is spun, the disk contains both potential and kinetic energy. The potential energy is given to the disk when it is placed upright on its side. The kinetic energy is given to the disk when it is spun on the mirrored base. Euler's Disk would spoll (i.e., spin and roll) forever it it were not for friction and vibration.

Conservation of Angular Momentum:
Another way of describing how Euler's Disk operates is by considering the disk's angular momentum. Like a top, Euler's Disk uses its angular momentum to hold itself upright. As the disk spolls around in a circle it is held in place by a balance of the gravitational force pulling the disk down and the force applied by the mirror base which holds the disk up. Again, if it were not for friction and vibration, the disk would rotate for a very long time.