Unit 3 Nature’s Energy 1

4. Water Energy

Moving water can push on objects and move them Remember that any matter that is moving is using mechanical energy

This is called water energy So water is a source of mechanical energy This is called water energy

Energy that comes from the push of water Vocabulary Water energy Energy that comes from the push of water

A long time ago, people learned to use water energy for waterwheels Waterwheels are built on streams

A waterwheel is a large wheel with blades on it As water pushes on the blades, the wheel turns

Even today, energy from waterwheels is used to grind grain and to cut logs

When water falls from a high place to a lower place, it carries a lot of energy Dams are built on rivers and lakes to make use of this energy

Dams hold back a great amount of water This water is sent through pipes to water turbines hundreds of feet below.

A device that turns water energy into mechanical energy Vocabulary Water turbine A device that turns water energy into mechanical energy

A turbine is like a waterwheel, but it turns much faster The falling water turns the turbines

The water energy that the turbines collect is used to run a generator

A device that makes electricity by electromagnetic induction Vocabulary generator A device that makes electricity by electromagnetic induction

A lot of electricity can be made by dams Hoover Dam, on the border between Arizona and Nevada, is one of the highest dams in the world

Water is a good source of energy It does not pollute the air

But water power plants can be built only near a waterfall or a dam It will never run out But water power plants can be built only near a waterfall or a dam

dams cost a great deal of money to build Also, dams cost a great deal of money to build All energy cannot come from water energy