# Physics: Principles and Problems Chapter 11 Vocab

Rotational kinetic energy
The kinetic energy of an object, proportional to the object’s moment of inertia and the square of its angular velocity.

Gravitational potential energy
The stored energy in a system resulting from the gravitational force between Earth and the object.

Reference level
The position where gravitational potential energy is defined as zero.

Elastic potential energy
The potential energy that may be stored in an object, such as a rubber band, as a result of its change in shape.

Law of conservation of energy
States that in a closed, isolated system, energy is not created or destroyed, but rather, is conserved.

Mechanical energy
The sum of kinetic and gravitational potential energy of a system.

Thermal energy
A measure of the internal motion of an object’s particles.

Elastic collision
A type of collision in which the kinetic energy before and after the collision remains the same.

Inelastic collision
A type of collision in which the kinetic energy after the collision is less than the kinetic energy before the collision.