Across
- 5. any natural material that is used by humans such as water, petroleum, minerals, forests, and animals.
- 6. a resource that forms at a rate that is much slower than the rate at which it is consumed.
- 8. energy produced by heat within the earth
- 9. organic matter that can be a source of energy.
Down
- 1. electrical energy produced by falling water
- 2. a natural resource that can be replaced at the same rate at which the resource is consumed.
- 3. a nonrenewable energy resource formed from the remains of organisms that lived long ago. Examples: petroleum, coal, oil, natural gas.
- 4. the energy that is released by a fission or fusion reaction of the element uranium, nonrenewable.
- 7. the energy received by the Earth from the sun in the form of radiation.