And so as the marker travels, its gravitational potential energy will begin to decrease. The question is, where does that gravitational potential energy actually go? Well, that energy cannot be destroyed by the first law of thermodynamics. And what happens to it is that gravitational potential energy begins to transform into the energy of motion of that object known as the kinetic energy. So as the marker travels down, that potential energy is being transformed into kinetic energy. And the same exact is true.