Question

Explain why water stored in a dam has potential energy.

Answer 1

The potential energy of the water in a dam corresponds to the height of the water. Any substance or object at a height above the ground will have energy corresponding to the height of the object above the ground.

Complete step by step answer:
Dams are large reservoirs of water that are built at a height above the ground such that they stop the flow of water and store it. In the absence of the dams, the water would flow downstream. However, the dam stops the flow of the water and accumulates the water in it. This increases the height of the water with respect to the ground.
Since the water has a height above the ground, it will have stored potential energy. This potential energy can also be thought of as the tendency of the water to flow downstream if the dam gates were opened. The potential energy corresponds to the potential energy of the water in Earth’s gravity since it is at a height above the ground.
Additional information:
It is this stored potential energy that is converted to electrical energy in hydropower plants. The dams restrict the natural flow of water and instead make it flow slowly through the turbines of the power plant hereby generating electricity. However, to have sufficient electricity, there must be a sufficient amount of supply of water in the dam.

Note: The formula of the potential energy for an object of mass $m$ at height $h$ is given as $U = mgh$ where $g$ is the gravitational acceleration. The higher the height of the dam with respect to the ground, the higher is the potential energy stored in the dam.