The Spring, like all objects, tends to resist change in its motion. Because of this inertia, if it were placed at the top of the stairs it would stay at rest without moving at all. At this point it has potential or stored energy. But once it is started down the stairs and gravity affects it, the potential energy is converted to the energy of motion or kinetic energy and the Spring gracefully tumbles coil by coil down the stairs.
The physical properties of the spring determine how quickly it moves under the influence of gravity. As the spring moves down the steps, energy is transferred along its length in a longitudinal or compressional wave, which resembles a sound wave that travels through a substance by transferring a pulse of energy to the next molecule. How quickly the wave moves depends on the spring constant and the mass of the metal. Other factors, such as the length of the spring, the diameter of the coils and the height of the step must be considered to completely understand why a spring moves as it does.
