Question

Two different rivers have drops that are the same height. In river A, this section of the river is a waterfall. In river B, this section has a hydroelectric dam. In what way does the energy differ between the drops in the two rivers?

The potential energy of the water would be less at the top of the drop in river A than in river B.

The kinetic energy of the water would be less at the bottom of the drop in river A than in river B.

The potential energy of the water would be greater at the top of the drop in river A than in river B.

The kinetic energy of the water would be greater at the bottom of the drop in river A than in river B.

Answer 1

The kinetic energy of the same amount of water would be greater at the bottom of the drop of river A (waterfall) than in river B (hydroelectric dam.)

Step-by-step explanation:

In a uniform gravitational field, the gravitational potential energy of an object is proportional to height relative to the ground. It is given that the top of the two drops are of the same height. As a result, the same amount of water at the top of the drops would have the same amount of gravitational potential energy.

When water moves from the top of the drop to the bottom, gravitational potential energy is converted into kinetic energy.

In the waterfall of river A, the change in potential energy is nearly entirely converted into kinetic energy. However, in river B, some of that potential energy is converted into the mechanical energy of the hydroelectric generators. Since energy is conserved, the same amount water at the bottom of the river B drop would have less kinetic energy.