Nature of EnergyNature of Energy

Pgs. 402 - 414Pgs. 402 - 414

The Mysterious EverythingWhat is this stuff?

Whatever happens is caused by it. Whatever is, is made up of it.You need it, you are made up of it.

Everything needs it. Everything is it. It is everything!You need it to run, to walk, to sit,

to think, to sleep, "perchance to dream", to eat, "perchance to belch."You use it constantly, every moment, awake or asleep.

You can't get mad without it.You can't get glad without it

You can't get anything without it.It makes the wind blow, rain fall and lightning zap and thunder.

It "feeds" volcanoes and earthquakes. It drives tidal waves, typhoons, and tornadoes.It powers the universe!

It is the Mysterious Everything.Let's call it ME for short.WHAT IS THIS STUFF?

What is energy?What is energy? Energy is the ability to Energy is the ability to

do work or cause do work or cause changechange

Work happens when a Work happens when a force moves an object force moves an object through a distancethrough a distance

Force is a push or pullForce is a push or pull Work can also be Work can also be

thought of as the thought of as the transfer of energy.transfer of energy.

A joule is the metric unit used for energy and work!

Transferring EnergyTransferring Energy

Everything around you has energy.Everything around you has energy. You notice energy when a change takes You notice energy when a change takes

place.place. Anytime a change occurs, energy is Anytime a change occurs, energy is

transferred from one object to another.transferred from one object to another.

Transfer of Energy Transfer of Energy ExamplesExamples

Someone’s foot hits the floor and you Someone’s foot hits the floor and you hear a sound.hear a sound.

The top of your desk becomes warm The top of your desk becomes warm when the sun shines on it.when the sun shines on it.

A CD player is plugged up and turned on. A CD player is plugged up and turned on. The CD turns, and you hear music. 3 The CD turns, and you hear music. 3 energy transfers have occurred. energy transfers have occurred. Electrical -Electrical - Mechanical Mechanical SoundSound

Kinetic EnergyKinetic Energy

2 kinds of energy2 kinds of energy Kinetic energy (energy being transferred)Kinetic energy (energy being transferred) Potential energy (energy being stored)Potential energy (energy being stored)

Kinetic energy is energy in motionKinetic energy is energy in motion An object’s kinetic energy depends on its An object’s kinetic energy depends on its

mass and velocitymass and velocity Mass – amount of matter in an objectMass – amount of matter in an object Velocity – speed in a given directionVelocity – speed in a given direction

Kinetic energy needs Kinetic energy needs mass & velocity?mass & velocity?

If the mass of an object increases, its kinetic If the mass of an object increases, its kinetic energy increases.energy increases.

If the velocity of an object increases, its kinetic If the velocity of an object increases, its kinetic energy increases. energy increases.

All energy and work are measured in joules.All energy and work are measured in joules.

Marble Experiment

Calculating Kinetic Calculating Kinetic EnergyEnergy

Kinetic Energy = Kinetic Energy = Mass x VelocityMass x Velocity22

22

3 x 9 3 x 9 = = 2727 = 13.5 joules = 13.5 joules 2 2 2 2

Plug in the following values and see how kinetic energy Plug in the following values and see how kinetic energy changes.changes.

Mass = 3, velocity = 6Mass = 3, velocity = 6Mass = 6, velocity = 3Mass = 6, velocity = 3

CHECKPOINT CHECKPOINT

Which has the greatest kinetic energy: a Which has the greatest kinetic energy: a motorcycle moving at 30 km/hour, a four-motorcycle moving at 30 km/hour, a four-door car moving at 30 km/hour, or a truck door car moving at 30 km/hour, or a truck sitting on top of a hill?sitting on top of a hill?

Potential EnergyPotential Energy

Energy that is stored and Energy that is stored and NOT IN MOTIONNOT IN MOTION

2 types of potential energy2 types of potential energy Elastic potential energy – Elastic potential energy –

potential energy associated potential energy associated with objects that can be with objects that can be stretched or compressedstretched or compressed

Gravitational potential energy Gravitational potential energy – potential energy associated – potential energy associated with heightwith height

Elastic Potential Energy

CHECKPOINT CHECKPOINT

What is the unit for work and energy? What is the unit for work and energy?

Joule or Newton-meter

Calculating Gravitational Calculating Gravitational Potential EnergyPotential Energy

GPE = weight x height (unit is joules)GPE = weight x height (unit is joules) The greater the weight of an object or the The greater the weight of an object or the

greater the height it is lifted, the greater is greater the height it is lifted, the greater is its GPEits GPE

If you don’t have weight but have the If you don’t have weight but have the mass, you must multiply the mass by 9.8 mass, you must multiply the mass by 9.8 m/sm/s22 in order to convert it to the weight in in order to convert it to the weight in newtons.newtons.

CHECKPOINT CHECKPOINT

Describe how the ball experiment is an Describe how the ball experiment is an example of gravitational potential energy.example of gravitational potential energy.

Let’s Review!Let’s Review!

Different Forms of EnergyDifferent Forms of Energy

1.1. Mechanical EnergyMechanical Energy

2.2. Thermal EnergyThermal Energy

3.3. Chemical EnergyChemical Energy

4.4. Electrical EnergyElectrical Energy

5.5. Electromagnetic Electromagnetic EnergyEnergy

6.6. Nuclear EnergyNuclear Energy

Energy transformations occur constantly all Energy transformations occur constantly all around you.around you.

Many machines are devices that transform Many machines are devices that transform energy from one form to another.energy from one form to another.

Example: An automobile engine transforms Example: An automobile engine transforms the chemical energy in gasoline into energy the chemical energy in gasoline into energy of motion.of motion.

Mechanical EnergyMechanical Energy

Energy associated with the motion or Energy associated with the motion or position of an objectposition of an object Can be potential or kineticCan be potential or kinetic

Thermal EnergyThermal Energy

Energy of particles in Energy of particles in an objectan object

When particles move When particles move faster, more heat is faster, more heat is generatedgenerated

When particles move When particles move slower, less heat is slower, less heat is generatedgenerated

Food Coloring Experiment

HOW THERMAL ENERGY MOVESHOW THERMAL ENERGY MOVES Thermal energy only moves from Thermal energy only moves from

something warm to something cool.something warm to something cool.

Example: Hot chocolate’s thermal energy Example: Hot chocolate’s thermal energy moves from the cup to the cooler spoon moves from the cup to the cooler spoon and to the cooler air around it.and to the cooler air around it.

Chemical EnergyChemical Energy

Potential energy stored in chemical Potential energy stored in chemical bonds that hold chemical compounds bonds that hold chemical compounds togethertogether

In your body, the transformation of chemical In your body, the transformation of chemical to kinetic energy occurs in muscle cells. to kinetic energy occurs in muscle cells.

Electrical EnergyElectrical Energy

Moving electric charges producing Moving electric charges producing electricityelectricity

Generating Electrical EnergyGenerating Electrical Energy The enormous amount of electrical energy The enormous amount of electrical energy

that is used everyday is generated by that is used everyday is generated by power plants.power plants.

Every power plant works on the same Every power plant works on the same principle---energy is used to turn a large principle---energy is used to turn a large generator.generator.

A A generator generator is a device that transforms is a device that transforms kinetic energy into electrical energy.kinetic energy into electrical energy.

In fossil fuel power plants, coal, oil, or In fossil fuel power plants, coal, oil, or natural gas is burned to boil water.natural gas is burned to boil water.

As the hot water boils, steam rushes As the hot water boils, steam rushes through a through a turbineturbine, a device which contains a , a device which contains a set of narrowly spaced fan blades. The set of narrowly spaced fan blades. The steam pushes on the fan blades and turns steam pushes on the fan blades and turns the turbine. The turbine, in turn, rotates a the turbine. The turbine, in turn, rotates a shaft in the generator to produce electricity.shaft in the generator to produce electricity.

Electromagnetic EnergyElectromagnetic Energy

Has both electric properties and magnetic propertiesHas both electric properties and magnetic properties Travels in waves and includes microwaves, Travels in waves and includes microwaves,

ultraviolet radiation, infrared radiation, and visible ultraviolet radiation, infrared radiation, and visible lightlight

Nuclear EnergyNuclear Energy

Type of potential energy stored in the Type of potential energy stored in the nucleus of an atomnucleus of an atom

One type of nuclear energy is called One type of nuclear energy is called nuclear fission (nucleus splits apart)nuclear fission (nucleus splits apart)

Another type of nuclear energy is called Another type of nuclear energy is called nuclear fusion (many nuclei fuse together)nuclear fusion (many nuclei fuse together)

Nuclear fission

Nuclear fusion