Final answer:
A cowboy and his horse standing on a cliff represent an example of potential energy, specifically gravitational potential energy due to their elevated position, which could convert to kinetic energy if they were to move.
Step-by-step explanation:
The scenario of a cowboy and his horse standing on a cliff watching the sunset can be classified as an example of potential energy. This type of energy is related to the position of an object and the gravitational pull it experiences. In this case, the cowboy and his horse have gravitational potential energy due to their position high above the ground. This energy has the potential to be converted into kinetic energy if they were to move or fall off the cliff. In physics, this relates to the Law of Conservation of Mechanical Energy, which states that the total mechanical energy (potential plus kinetic) in a closed system remains constant given no external dissipative forces.