Final answer:
A waterfall contains potential energy, which can transform into kinetic energy as water falls and can be used for processes like electricity generation.
Step-by-step explanation:
The type of resource present in a waterfall can best be described as potential energy. This is because the water at the top of the waterfall has stored energy due to its high elevation. As it falls, the potential energy is converted into kinetic energy, which can be used to do work, such as turning turbines for electricity generation in a hydroelectric power plant, as depicted in Figure 15.1.3. This transformation is analogous to the potential energy of a tree trunk at the top of a waterfall being converted to kinetic energy as it falls. This process is exemplified by installations like the Hoover Dam, where flowing water is utilized to produce electrical energy.