ENERGY Energy is defined as the ability to do work or cause change. **Work is when a force moves an object.

POTENTIAL AND KINETIC

POTENTIAL  Potential energy is energy that is STORED in an object.  Energy can be stored due to the position of the object or chemically. Examples include: Batteries Water behind a dam A rock at the top of a hill Oil and coal Food

EXAMPLES

KINETIC  Energy of motion.  The amount of kinetic energy an object has depends on it’s mass and speed. Examples include: An engine running Water falling over a dam Windmill turning Lightbulb shining A ball rolling down a ramp

Examples of Kinetic Energy

Roller Coaster Kinetic and potentialRoller Coaster Kinetic and potential Golf swing kinetic and potentialGolf swing kinetic and potential Clips about Kinetic and Potential Wile Coyote’s Struggles with Potential and Kinetic

BACK AND FORTH Energy can switch back and forth between potential and kinetic. Think of a roller coaster. A chain pulls the cart up to the top of the first hill ( Kinetic to potential). The coaster has maximum potential at the top. As the cart falls down the hill the potential turns to kinetic with full kinetic at the bottom, and begins again.

FORMS OF ENERGY Different ways that objects can possess energy Mechanical Chemical Thermal (Heat) Electrical Electromagnetic Nuclear Sound

Energy of movement, like kinetic energy. Examples: Walking, a car moving, a ball being kicked or hit with a bat. MECHANICAL

CHEMICAL Energy stored in chemical bonds of compounds. This energy is released when we break up the compound. Examples include when we burn oil or digest food.

THERMAL (HEAT) Energy given off as heat. The amount of heat energy an object has is measured in degrees.

ELECTRICAL Electrical energy is the transfer of electrons from one atom to another. The moving electrons are called “current”

ELECTROMAGNETIC Electromagnetic energy is energy that travels in waves. The sun’s energy travels to us as electromagnetic waves. The energy is carried in small packages called photons.

NUCLEAR Nuclear energy involves changes in the nucleus of atoms. Nuclear energy powers the sun and occurs on earth in the atoms of radioactive elements mostly in the core of the earth.

MORE CHANGE Energy has the ability to change forms. Chemical energy of food becomes mechanical energy of moving muscles. Mechanical energy of moving wind can be changed by a turbine into electrical energy.

SOLAR ENERGY/SOLAR RADIATION The sun is a giant nuclear furnace that sends out a constant stream of energy in the form of radiation. Solar radiation is classified into groups based on wavelength.

Greenhouse Effect 1. Earth has a layer of gases that surrounds it called the atmosphere. 2. This layer acts like glass in a car or building and lets light in. Some of the light/heat leaves but some is trapped and this keeps the earth warm at night. 3. Certain gases hold more heat than others. These greenhouse gases are slowly making the earth warmer

HUMANS USE LOTS OF ENERGY Our society is dependent on having free flowing sources of energy. Especially electricity Where do we get all of this energy? How do we classify our energy sources?

What do we use energy for? Food Heat our homes __________________________ This demand for energy will not change

We classify our energy sources into two groups Renewable Non-Renewable

RENEWABLE ENERGY SOURCES Energy that is constantly being produced or can be replaced within several years or less. Examples include SolarBiomass WindHydro ( moving water) Geothermal

Some advantages of renewable energy sources Saves burning fossil fuels Creates less pollution There is a constant supply

GEOTHERMAL Thermal energy that comes from inside the earth. Radioactive elements deep in the core of the earth produce heat that warms rock and water. Warm water is often used as a source of heat for homes.

WIND Wind is formed when 1) The ground heats up (from the sun’s energy) 2) The air touching the ground heats and rises. Moving air is wind

SOLAR ENERGY We use forms of energy from the sun Heat (thermal) and electromagnetic(radiant). Radiant energy can be changed into clean energy using photovoltaic cells.

RADIANT ENERGY Heat from the sun is absorbed by dark surfaces and is used to heat water in solar heaters. This heat transfer in waves is called radiation heat transfer. Solar heaters on roof tops work this way

Solar light energy Visible light from the sun is transformed into electrical energy in solar cells (photovoltaic). Calculators and large solar cells in the desert are examples.

HYDROELECTRIC The mechanical energy of moving water is changed into electricity in turbines. Sources of moving water include rivers and in some places the tides.

Biomass Fuel which is made from things that were once alive. Wood Corn Manure (yes-you read it right) Leaves Garbage

Hydrogen Fuel Cells

Disadvantages of renewable fuel sources Not available in all areas: some areas do not have wind, or tides or places to grow trees. Not all machines are designed to use these types of fuel sources. Costly. Most machines are designed to run on fossil fuels.

NON-RENEWABLE Fuel resources that are not replaceable within millions years. Most nonrenewable fuels are FOSSIL FUELS Coal petroleum Natural Gas *Nuclear Fuel is considered Non-renewable*

What is a fossil fuel? Fossil fuels are the remains of ancient organisms changed by time, heat and pressure. Fossil fuels are rich in the elements hydrogen and carbon. Energy from the sun is stored in fossil fuels as chemical potential energy.

EXAMPLES OF FOSSIL FUELS PETROLEUM COAL NATURAL GAS

Uses of Fossil Fuels 1)Industry: Used to make fabric and run machines 2)Transportation: Gasoline is made from Petroleum 3)To produce electricity (see next page for picture)

Coal to Electricity

What we use petroleum for Petroleum is used to make……….. Gasoline and oils Plastics Synthetic fabrics

Disadvantages of Fossil Fuels They pollute the atmosphere They will not always be available because we are using them up and take millions of years to replace.

Why do we still use Nonrenewable fuels? They are still relatively inexpensive. They produce a lot of power. Most of our machines are designed to run on gas or oil from fossil fuels.