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EnergyEnergy
Nature of EnergyNature of Energy
Energy is all around you.Energy is all around you. You hear energy as sound You hear energy as sound
You see energy as lightYou see energy as light
Nature of EnergyNature of Energy
You can feel energy in windYou can feel energy in wind
Nature of EnergyNature of Energy
Living organisms need energy for growth Living organisms need energy for growth and movementand movement
Nature of EnergyNature of Energy
You use energy whenYou use energy when You hit a tennis ballYou hit a tennis ball Compress a springCompress a spring Lift a grocery bagLift a grocery bag
Energy is …Energy is … The ability to do work!The ability to do work! The energy released by a supernova is The energy released by a supernova is
capable of destroying a nearby solar capable of destroying a nearby solar system in just a few hours. A supernova system in just a few hours. A supernova is one of the greatest concentrations of is one of the greatest concentrations of energy in the universe.energy in the universe.
Forms of EnergyForms of Energy
Energy appears in many forms. There Energy appears in many forms. There are five main forms of energy.are five main forms of energy. Mechanical Mechanical HeatHeat ChemicalChemical ElectromagneticElectromagnetic NuclearNuclear
Mechanical EnergyMechanical Energy
Energy of motionEnergy of motion Examples includeExamples include
Water in a waterfallWater in a waterfall WindWind Moving vehiclesMoving vehicles SoundSound
Heat EnergyHeat Energy The internal motion of atoms.The internal motion of atoms. The faster the molecules move, the more The faster the molecules move, the more
heat energy is produced.heat energy is produced. Examples includeExamples include
FrictionFriction Changes in the state of matterChanges in the state of matter
Chemical EnergyChemical Energy
Energy that exists in the bonds that hold Energy that exists in the bonds that hold atoms together.atoms together.
When bonds are broken chemical energy When bonds are broken chemical energy is released.is released.
Examples includeExamples include Digesting food … bonds are broken to Digesting food … bonds are broken to
release energy for your body to store and release energy for your body to store and use.use.
Chemical Energy (cont)Chemical Energy (cont)
More examplesMore examples Sports … your body uses energy stored in Sports … your body uses energy stored in
your muscles obtained from food.your muscles obtained from food. Fire – a chemical changeFire – a chemical change
Electromagnetic EnergyElectromagnetic Energy
Moving electric charges.Moving electric charges. Examples includeExamples include
Power lines carry electricityPower lines carry electricity Electric motors are driven by Electric motors are driven by
electromagnetic energyelectromagnetic energy
Electromagnetic Electromagnetic SpectrumSpectrum
Light is just one of the forms of energy Light is just one of the forms of energy that fall in the electromagnetic spectrum.that fall in the electromagnetic spectrum.
Nuclear EnergyNuclear Energy
When the nucleus of an atom splits, When the nucleus of an atom splits, nuclear energy is released.nuclear energy is released.
Nuclear energy is the most concentrated Nuclear energy is the most concentrated form of energy.form of energy.
Nuclear Energy (cont.)Nuclear Energy (cont.) Nuclear Fission - is a nuclear reaction in Nuclear Fission - is a nuclear reaction in
which the nucleus of an atom splits into which the nucleus of an atom splits into smaller parts; which can release large smaller parts; which can release large amounts of energy both as electromagnetic amounts of energy both as electromagnetic radiation and as kinetic energy of the radiation and as kinetic energy of the fragments fragments
Nuclear Energy (cont.)Nuclear Energy (cont.) Nuclear Fusion - is the process in which two Nuclear Fusion - is the process in which two
or more atomic nuclei join together, or or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. "fuse", to form a single heavier nucleus. This is usually accompanied by the release This is usually accompanied by the release or absorption of large quantities of energy. or absorption of large quantities of energy.
QuestionsQuestions
What is energy?What is energy? Can energy be transferred from one Can energy be transferred from one
object to another?object to another? What are the different forms of energy?What are the different forms of energy?
States of EnergyStates of Energy
There are two states of energyThere are two states of energy PotentialPotential KineticKinetic
Potential EnergyPotential Energy Stored energy – energy of position.Stored energy – energy of position. Not always mechanical energy – can be Not always mechanical energy – can be
other forms.other forms. Gravitational Potential energy depends Gravitational Potential energy depends
on height and weight.on height and weight. GPE = Weight x HeightGPE = Weight x Height Units –Newton/meterUnits –Newton/meter
Kinetic EnergyKinetic Energy The energy of motion.The energy of motion. The faster the object moves – the more The faster the object moves – the more
kinetic energy.kinetic energy. Kinetic energy depends on both mass Kinetic energy depends on both mass
and velocity.and velocity. KE = ½ (mass x velocityKE = ½ (mass x velocity22)) Kg mKg m22/s/s22
Units - JoulesUnits - Joules
Wasted EnergyWasted EnergyWhenever an energy transfer occurs some energy is ALWAYS WASTED. Where does this energy go to?
It SPREADS OUT and is LOST to the SURROUNDINGS. It is very hard to REUSE. This is why we should be mindful not to waste energy needlessly.
What is the wasted energy for an electrical lamp?
A lamp is designed to change electrical energy into light energy.
Some energy is wasted in the form of HEAT though. In fact, ALL ELECTRICAL devices WASTE ENERGY in the form of HEAT.
If you could hear the lamp buzzing then it would be wasting energy in the form of SOUND.
Exercise 8: Wasted EnergyExercise 8: Wasted Energy
1. What happens to wasted energy?
2. In which two forms is energy usually wasted?
3. In what form do all electrical devices waste energy?
4. If you can hear a device that is not supposed to make a noise, in what form is energy being wasted?
5. In what forms does a hairdryer waste energy?
6. In what form does a coal fire waste energy?
It spreads out into the surroundings and is harder to reuse.
Heat and sound.
Heat.
Sound.
Heat and sound.
Light energy.
Energy ConversionsEnergy Conversions The most common energy conversion The most common energy conversion
involves the changing of potential energy involves the changing of potential energy into kinetic energy or vice-versa.into kinetic energy or vice-versa.
Examples includeExamples include Ball thrown in the airBall thrown in the air Roller coasterRoller coaster
More ConversionsMore Conversions
All forms of energy can be converted to All forms of energy can be converted to other forms.other forms.
Law of Conservation of Energy – Energy Law of Conservation of Energy – Energy cannot be created or destroyedcannot be created or destroyed..
Einstein said – If matter is destroyed, Einstein said – If matter is destroyed, energy is created; if energy is destroyed, energy is created; if energy is destroyed, matter is created. The total amount of matter is created. The total amount of mass and energy is conserved.mass and energy is conserved.
