Abstract Noun - Angular momentum is a physics term used to describe the relationship between the center of mass and the speed of rotation of any object. A rotating object with a wide center of mass will increase the speed of rotation when the center of mass is narrowed. Think of a figure skater who spins with her arms outward, and then pulls her arms in toward her body to change her center of mass to increase her spin speed. This works on the exact same principle.
By changing her angular momentum, Nancy was able to pull off some amazing spinning moves on the ice, and win the competition in spite of being pummeled in the kneecaps by one of Tonya's thugs.