Nature of EnergyNature of Energy

Energy is all around you!Energy is all around you! You can hear energy as sound.You can hear energy as sound. You can see energy as light.You can see energy as light. And you can feel it as wind.And you can feel it as wind.

Energy is usually described Energy is usually described as kinetic or potentialas kinetic or potential

Thermal or Heat EnergyThermal or Heat Energy

The internal motion of the The internal motion of the atoms is called heat energy, atoms is called heat energy, because moving particles because moving particles produce heat.produce heat.

Heat energy can be produced Heat energy can be produced by friction.by friction.

Heat energy causes changes in Heat energy causes changes in temperature and phase of any temperature and phase of any form of matter.form of matter.

Chemical EnergyChemical Energy Chemical Energy is required to bond atoms Chemical Energy is required to bond atoms

together.together. And when bonds are broken, energy is And when bonds are broken, energy is

released.released. Fuel and food are formsFuel and food are forms

of stored chemical energyof stored chemical energy

Electromagnetic EnergyElectromagnetic Energy Light is a form of electromagnetic energy.Light is a form of electromagnetic energy. Each color of light (Roy G Biv) represents a Each color of light (Roy G Biv) represents a

different amount of electromagnetic energy.different amount of electromagnetic energy. Electromagnetic Energy is also carried by X-rays, Electromagnetic Energy is also carried by X-rays,

radio waves, and laser light.radio waves, and laser light.

Electromagnetic SpectrumElectromagnetic SpectrumIncreasing Energy

Electromagnetic Electromagnetic EnergyEnergy

Power lines carry Power lines carry electromagnetic energy into your electromagnetic energy into your home in the form of electricity.home in the form of electricity.

Nuclear EnergyNuclear Energy The nucleus of an atom is the source of The nucleus of an atom is the source of

nuclear energy. nuclear energy. When the nucleus splits (fission), nuclear When the nucleus splits (fission), nuclear

energy is released in the form of heat energy energy is released in the form of heat energy and light energy.and light energy.

Nuclear energy is also released when nuclei Nuclear energy is also released when nuclei collide at high speeds and join (fuse).collide at high speeds and join (fuse).

Nuclear Power PlantNuclear Power Plant

Nuclear EnergyNuclear Energy

The sun’s energy is produced from a nuclear fusion reaction in which hydrogen nuclei fuse to form helium nuclei.

Mechanical EnergyMechanical Energy

Mechanical energy is due to Mechanical energy is due to the position and motion of the position and motion of the object.the object.

When work is done to an When work is done to an object, it acquires energy. object, it acquires energy. The energy it acquires is The energy it acquires is known as mechanical known as mechanical energy.energy.

Mechanical EnergyMechanical Energy

What happens to the mechanical What happens to the mechanical energy of an apple as it falls from a energy of an apple as it falls from a tree?tree?

Mechanical EnergyMechanical Energy As the apple falls to the ground, its height As the apple falls to the ground, its height

decreases. decreases. Therefore, its GPE decreases.Therefore, its GPE decreases. Potential Potential

energy that is dependent on height is called energy that is dependent on height is called gravitational potential energygravitational potential energy..

The potential energy is not lost… it is The potential energy is not lost… it is converted into kinetic energy as the velocity of converted into kinetic energy as the velocity of the apple increases.the apple increases.

What happens to the mechanical energy?What happens to the mechanical energy?

Mechanical EnergyMechanical Energy

The mechanical energy does not change The mechanical energy does not change because the loss in potential energy is because the loss in potential energy is simply transferred into kinetic energy.simply transferred into kinetic energy.

The energy in the system remains The energy in the system remains constant!!constant!!

Swinging AlongSwinging Along

Think about the changes in energy when Think about the changes in energy when you are on a swing…you are on a swing…

At what point do you have the most At what point do you have the most potential energy?potential energy?

At what point do you have the most At what point do you have the most kinetic energy?kinetic energy?

What happens to the mechanical What happens to the mechanical energy?energy?

Conservation of EnergyConservation of Energy Energy is transformed… not destroyed!!Energy is transformed… not destroyed!!

The Law of Conservation of Energy

• The law of conservation of energy states that energy cannot be created or destroyed.

• Energy can be changed from one form to another. Changes in the form of energy are called

energy conversions.

Energy Conversion Energy Conversion ExamplesExamples

The Law of Conservation of Energy

• Even when energy changes form from electrical to thermal and other energy forms as in the hair

dryer shown energy is never destroyed.

The Law of Conservation The Law of Conservation of Energyof Energy

The Law of Conservation of Energy The Law of Conservation of Energy states that energy cannot be created or states that energy cannot be created or destroyed.destroyed.

The big picture… the total energy in the The big picture… the total energy in the universe remains constant.universe remains constant.

Changing Forms of Changing Forms of EnergyEnergy

Energy is most noticeable as it Energy is most noticeable as it transforms from one type to another.transforms from one type to another.

What are some examples of transforming What are some examples of transforming electrical energy?electrical energy? A lightbulbA lightbulb A hair dryerA hair dryer

The most common energy The most common energy conversion is between potential conversion is between potential and kinetic energy.and kinetic energy.

All forms of energy can be in either All forms of energy can be in either of two states:of two states:Kinetic is the energy of motion.Kinetic is the energy of motion.Potential is stored energyPotential is stored energy

Potential to KineticPotential to Kinetic

Changing forms of Changing forms of EnergyEnergy An example of transforming chemical An example of transforming chemical

energy is a car engine. energy is a car engine. Chemical potential energy in gasoline is Chemical potential energy in gasoline is

transformed into kinetic energy of the car transformed into kinetic energy of the car as it moves!!as it moves!!

Energy transfer Energy transfer

PhotosynthesisPhotosynthesis Photosynthesis Photosynthesis

changes light energy changes light energy into food (chemical) into food (chemical) energy. energy.

Plants convert the Plants convert the energy of sunlight into energy of sunlight into the energy of chemical the energy of chemical bonds of carbohydratesbonds of carbohydrates

http://www.eia.doe.gov/kids/energyfacts/sources/renewable/images/photosynthesis1.gif

Digestion is the process in Digestion is the process in the body that breaks these the body that breaks these chemical bonds and chemical bonds and releases the chemical releases the chemical

energy in foodsenergy in foods

This chemical potential This chemical potential energy is changed into energy is changed into kinetic energy as your body kinetic energy as your body movesmoves

Energy conversion

Conserving EnergyConserving Energy

When you “use” energy When you “use” energy by turning on a light, you by turning on a light, you are really converting are really converting energy from one form energy from one form (electricity) to other (electricity) to other forms (light and heat).forms (light and heat).

How does the bulb light up?How does the bulb light up?What forms of energy are What forms of energy are seen?seen?

The bulb gets its energy from The bulb gets its energy from the battery.the battery.

There is chemical energy in There is chemical energy in the batterythe battery

Electrical energy in the wiresElectrical energy in the wires Thermal energy in the bulb Thermal energy in the bulb

filamentfilament Light energy and thermal Light energy and thermal

energy seen from the bulb.energy seen from the bulb. Energy changes form to light Energy changes form to light

the bulb.the bulb.

Conserving EnergyConserving Energy Electric power plants don’t Electric power plants don’t make make electrical energy. electrical energy. Energy cannot be created. Energy cannot be created. Energy CAN be converted from other forms of Energy CAN be converted from other forms of

energy such as chemical, solar, or nuclear energy.energy such as chemical, solar, or nuclear energy.

Conserving EnergyConserving Energy

An average electric An average electric power plant puts out power plant puts out 1,000,000 kwh of 1,000,000 kwh of electrical energy per electrical energy per hour. hour.

That means 120 power That means 120 power plants are burning up plants are burning up resources each hour just resources each hour just to run light bulbs!to run light bulbs!

Solar Energy• Solar Power, along with wind and hydroelectric

account for most of the renewable energy source available to use.

• Solar energy can be collected by humans through photovoltaics or solar panels. 

What do the photovoltaic and the wheat What do the photovoltaic and the wheat plant, shown in the images below, have in plant, shown in the images below, have in common?common?

Photovoltaic WheatPhotovoltaic Wheat

ANSWER: They both convert sunlight, ANSWER: They both convert sunlight, (electromagnetic energy), into chemical (electromagnetic energy), into chemical potential energypotential energy

The photovoltaic absorbs solar energy and The photovoltaic absorbs solar energy and stores it as chemical potential energy in stores it as chemical potential energy in batteries.batteries.

The leaves of the wheat plant absorb solar The leaves of the wheat plant absorb solar energy which is (mainly) stored as chemical energy which is (mainly) stored as chemical potential energy in compounds called potential energy in compounds called carbohydrates.carbohydrates.

Kinetic EnergyKinetic Energy The faster an object moves, the more The faster an object moves, the more

kinetic energy it has.kinetic energy it has. The greater the mass of a moving The greater the mass of a moving

object, the more kinetic energy it has.object, the more kinetic energy it has. Kinetic energy depends on both mass Kinetic energy depends on both mass

and velocity.and velocity.

Kinetic EnergyKinetic Energy

K.E. = K.E. = mass x velocitymass x velocity

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What has a greater effect on kinetic energy, What has a greater effect on kinetic energy, mass or velocity? Why?mass or velocity? Why?

the velocity because it is being squared so it is increasing by a factor of 4

Potential EnergyPotential Energy ““The bigger they are the harder they The bigger they are the harder they

fall” is not just a saying. It’s true. fall” is not just a saying. It’s true. Objects with more mass have greater Objects with more mass have greater P.E.P.E.

The formula to find P.E. isThe formula to find P.E. is

P.E. = Weight X Height.P.E. = Weight X Height.

Ball slows down Ball speeds up

At the point of maximum potential energy, the car has minimum kinetic energy.