Which of the following is an example of potential energy?

Potential energy is the stored energy in an object due to its position or configuration. In this case, water behind a dam is a prime example of potential energy because it is held at a height, and this elevated position allows it to have the potential to do work when released. When the water flows downward due to gravity, it can turn turbines to generate electricity, thus converting that stored potential energy into kinetic energy.

The other options illustrate different forms of energy. For instance, flowing water represents kinetic energy due to its motion, while a car in motion also exemplifies kinetic energy as it is actively moving. Similarly, an electric current represents energy in the form of electrical kinetic energy due to the movement of electrons. Therefore, only the water behind a dam represents stored potential energy, making it the correct choice in the context of the question.