earths energy

the need for energy

Energy provides the ability to move or change matter from one state to another (for example, from solid to liquid). Every living thing needs energy to live and grow. Your body gets its energy from food, but that is only a small part of the energy you use every day. Cooking your food takes energy, and so does keeping it cold in the refrigerator or the freezer. The same is true for heating or cooling your home. Whether you are turning on a light in the kitchen or riding in a car to school, you are using energy. Billions of people all around the world use energy, so there is a huge demand for resources to provide all of this energy. Why do we need so much energy? The main reason is that almost everything that happens on Earth involves energy.

important things to consider about energy resources

Before we put effort into increasing the use of an energy source, we should consider two things. Is there a practical way to turn the resource into useful form of energy? For example, it is not practical if we dont get much more energy from burning a fuel than we put into making it. What happens when we turn the resource into energy? What happens when we use that resource? Mining the resource may cause a lot of health problems or environmental damage. Using the resource may create a large amount of pollution. In this case, that fuel may also not be the best choice for an energy resource.

kqed climate watch unlocking the grid

Today we rely on electricity more than ever, but the resources that currently supply our power are finite. The race is on to harness more renewable resources, but getting all that clean energy from production sites to homes and businesses is proving to be a major challenge. Learn more by watching the resource below: MEDIA Click image to the left or use the URL below. URL:

conservation of energy

Energy changes form when something happens. But the total amount of energy always stays the same. The Law of Conservation of Energy says that energy cannot be created or destroyed. Scientists observed that energy could change from one form to another. They also observed that the overall amount of energy did not change.

energy changes

Here is an example of how energy changes form: kicking a soccer ball. Your body gets energy from food. Where does the food get its energy? If youre eating a plant, then the energy comes directly from the Sun. If youre eating an animal, then the energy comes from a plant that got its energy from the Sun. Your body breaks down the food. It converts the food to chemical energy and stores it. When you are about to kick the ball, the energy must be changed again. Potential energy has the potential to do work. When your leg is poised to kick the ball but is not yet moving, your leg has potential energy. A ball at the top of a hill has the potential energy of location. Kinetic energy is the energy of anything in motion. Your muscles move your leg, your foot kicks the ball, and the ball gains kinetic energy (Figure 5.1). The kinetic energy was converted from potential energy that was in your leg before the kick. The action of kicking the ball is energy changing forms. The same is true for anything that involves change.

fuel

The energy to make the electricity comes from fuel. Fuel stores the energy and releases it when it is needed. Fuel is any material that can release energy in a chemical change. The food you eat acts as a fuel for your body. Gasoline and diesel fuel are fuels that provide the energy for most cars, trucks, and buses. But there are many different kinds of fuel. For fuel to be useful, its energy must be released in a way that can be controlled.

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heat

When fuel is burned, most of the energy is released as heat. Some of this heat can be used to do work. Heat cooks food or warms your house. Sometimes the heat is just waste heat. It still heats the environment, though. Heat from a fire can boil a pot of water. If you put an egg in the pot, you can eat a hard boiled egg in 15 minutes (cool it down first!). The energy to cook the egg was stored in the wood. The wood got that energy from the Sun when it was part of a tree. The Sun generated the energy by nuclear fusion. You started the fire with a match. The head of the match stores energy as chemical energy. That energy lights the wood on fire. The fire burns as long as there is energy in the wood. Once the wood has burned up, there is no energy left in it. The fire goes out.

the sources of earths energy

Almost all energy comes from the Sun. Plants make food energy from sunlight. Fossil fuels are made of the remains of plants and animals that stored the Suns energy millions of years ago. The Sun heats some areas more than others, which causes wind. The Suns energy also drives the water cycle, which moves water over the surface of the Earth. Both wind and water power can be used as renewable resources. Earths internal heat does not depend on the Sun for energy. This heat comes from remnant heat when the planet formed. It also comes from the decay of radioactive elements. Radioactivity is an important source of energy.

energy

What makes energy available whenever you need it? If you unplug a lamp, the light goes off. The lamp does not have a supply of energy to keep itself lit. The lamp uses electricity that comes through the outlet as its source of energy. The electricity comes from a power plant. The power plant has a source of energy to produce this electricity.

types of renewable resources

Renewable energy resources include solar, water, wind, biomass, and geothermal power. These resources are usually replaced at the same rate that we use them. Scientists know that the Sun will continue to shine for billions of years. So we can use the solar energy without it ever running out. Water flows from high places to lower ones. Wind blows from areas of high pressure to areas of low pressure. We can use the flow of wind and water to generate power. We can count on wind and water to continue to flow! Burning wood is an example of biomass energy. Changing grains into biofuels is biomass energy. Biomass is renewable because we can plant new trees or crops to replace the ones we use. Geothermal energy uses water that was heated by hot rocks. There are always more hot rocks available to heat more water. Even renewable resources can be used unsustainably. We can cut down too many trees without replanting. We might need grains for food rather than biofuels. Some renewable resources are too expensive to be widely used. As the technology improves and more people use renewable energy, the prices will come down. The cost of renewable resources will go down relative to fossil fuels as we use fossil fuels up. In the long run renewable resources will need to make up a large amount of what we use.

energy fuel and heat

Energy is the ability to do work. Fuel stores energy and can be released to do work. Heat is given off when fuel is burned.

types of energy resources

Energy resources can be put into two categories renewable or non-renewable. Nonrenewable resources are used faster than they can be replaced. Renewable resources can be replaced as quickly as they are used. Renewable resources may also be so abundant that running out is impossible. The difference between non-renewable and renewable resources is like the difference between ordinary batteries and rechargeable ones. If a flashlight when ordinary batteries goes dead, the batteries need to be replaced. But if the flashlight has rechargeable batteries, the batteries can be placed in a charger. The charger transfers energy from an outlet into the batteries. Once recharged, the batteries can be put back into the flashlight. Rechargeable batteries can be used again and again (Figure 5.2). In this way, the energy in the rechargeable batteries is renewable.

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types of nonrenewable resources

Fossil fuels include coal, oil, and natural gas. Fossil fuels are the greatest energy source for modern society. Millions of years ago, plants used energy from the Sun to form carbon compounds. These compounds were later transformed into coal, oil, or natural gas. Fossil fuels take millions of years to form. For this reason, they are non-renewable. We will use most fossil fuels up in a matter of decades. Burning fossil fuels releases large amounts of pollution. The most important of these may be the greenhouse gas carbon dioxide.

instructional diagrams

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questions

any material that stores energy and releases it in a chemical change

a. energy

b. chemical energy

c. kinetic energy

d. fossil fuel

e. potential energy

f. conservation of energy

-->  g. fuel

law that energy cannot be created or destroyed

a. energy

b. chemical energy

c. kinetic energy

d. fossil fuel

e. potential energy

-->  f. conservation of energy

g. fuel

energy that has the potential to do work

a. energy

b. chemical energy

c. kinetic energy

d. fossil fuel

-->  e. potential energy

f. conservation of energy

g. fuel

coal, oil, or natural gas

a. energy

b. chemical energy

c. kinetic energy

-->  d. fossil fuel

e. potential energy

f. conservation of energy

g. fuel

ability to move or change matter

-->  a. energy

b. chemical energy

c. kinetic energy

d. fossil fuel

e. potential energy

f. conservation of energy

g. fuel

form of energy obtained from food

a. energy

-->  b. chemical energy

c. kinetic energy

d. fossil fuel

e. potential energy

f. conservation of energy

g. fuel

energy of moving matter

a. energy

b. chemical energy

-->  c. kinetic energy

d. fossil fuel

e. potential energy

f. conservation of energy

g. fuel

Plants make food using energy from soil nutrients.

a. true

-->  b. false

Fossil fuels are made of minerals and rocks.

a. true

-->  b. false

Uneven heating by the sun causes wind.

-->  a. true

b. false

The suns energy drives the water cycle.

-->  a. true

b. false

Kicking a soccer ball changes kinetic energy to potential energy.

a. true

-->  b. false

The head of a match stores chemical energy.

-->  a. true

b. false

It takes millions of years for fossil fuels to form.

-->  a. true

b. false

Most fossil fuels will last for another 500 years.

a. true

-->  b. false

Trees are a source of biomass energy.

-->  a. true

b. false

Geothermal energy is a nonrenewable resource.

a. true

-->  b. false

Sources of energy on Earth include the

a. sun.

b. planets internal heat.

c. decay of radioactive elements.

-->  d. all of the above

What happens when energy changes form?

a. Some of the energy is lost.

b. The amount of energy increases.

c. The energy is generally used up.

-->  d. The amount of energy remains the same.

An example of potential energy is a child who is

a. running.

b. swimming.

-->  c. sitting at the top of a slide.

d. none of the above

An example of kinetic energy is a child who is

a. running.

b. swimming.

c. sliding down a slide.

-->  d. all of the above

Most electricity used in homes comes from

a. batteries.

-->  b. power plants.

c. biomass fuels.

d. solar energy.

Which statement is true of all renewable resources?

a. They will never run out.

b. They can be used unsustainably.

c. They have no drawbacks.

-->  d. none of the above

The energy stored in fossil fuels came originally from

a. rocks.

b. magma.

-->  c. the sun.

d. dinosaurs.

diagram questions

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