unit 3 energyandwork. energy energy is the ability to do work energy is all around us there are two...
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Unit 3Unit 3
Energy Energy
and and
WorkWork
EnergyEnergy
Energy is the ability to do workEnergy is the ability to do work
Energy is all around usEnergy is all around us
There are two basic kinds of energyThere are two basic kinds of energy
The two basic kinds of energy:The two basic kinds of energy:
Potential energyPotential energy
Kinetic energyKinetic energy
Potential EnergyPotential Energy
Potential energy is stored energyPotential energy is stored energy
There are two types of potential energyThere are two types of potential energy– Chemical potential energyChemical potential energy– Gravitational potential energyGravitational potential energy
Chemical Potential EnergyChemical Potential Energy
Chemical potential energy is energy that Chemical potential energy is energy that can be released as the result of a can be released as the result of a chemical reactionchemical reaction– Ex. Matches, food, gasolineEx. Matches, food, gasoline
Gravitational Potential EnergyGravitational Potential Energy
Gravitational potential energy is also Gravitational potential energy is also known as known as energy of positionenergy of position
Gravitational potential energy depends on Gravitational potential energy depends on an object’s an object’s weight and heightweight and height
Kinetic EnergyKinetic Energy
Kinetic energy is energy of motionKinetic energy is energy of motion
A moving object has kinetic energyA moving object has kinetic energy
Kinetic EnergyKinetic Energy
Kinetic energy depends on Kinetic energy depends on speed and speed and massmass– The faster an object is moving, the greater its The faster an object is moving, the greater its
kinetic energykinetic energy– The greater an object’s mass, the greater its The greater an object’s mass, the greater its
kinetic energykinetic energy
Forms of EnergyForms of Energy
There are five main forms of energyThere are five main forms of energy– Mechanical EnergyMechanical Energy– Electromagnetic EnergyElectromagnetic Energy– Heat EnergyHeat Energy– Chemical EnergyChemical Energy– Nuclear EnergyNuclear Energy
Mechanical EnergyMechanical Energy
The energy in moving thingsThe energy in moving things
– Includes soundIncludes sound
Electromagnetic EnergyElectromagnetic Energy
Energy in moving electronsEnergy in moving electrons
– Includes electricity and lightIncludes electricity and light
Heat EnergyHeat Energy
Energy in moving particles of matterEnergy in moving particles of matter
– The faster a particle moves, the more heat The faster a particle moves, the more heat energy it hasenergy it has
– All things contain some heat energyAll things contain some heat energy
Chemical EnergyChemical Energy
Energy that holds particles of matter Energy that holds particles of matter togethertogether
– Energy in fuel such as wood or coal is Energy in fuel such as wood or coal is chemical energychemical energy
Nuclear EnergyNuclear Energy
Energy stored in the nuclei of atomsEnergy stored in the nuclei of atoms
– Heat and light from the sun are produced from Heat and light from the sun are produced from nuclear energynuclear energy
EnergyEnergy
Energy can change from one form to Energy can change from one form to anotheranother
– When energy changes form, some of the When energy changes form, some of the energy is always changed into heat energyenergy is always changed into heat energy
– Most of this heat energy is lost as wasteMost of this heat energy is lost as waste
Thermal PollutionThermal Pollution
Thermal pollution is damage that occurs Thermal pollution is damage that occurs when waste heat enters the environmentwhen waste heat enters the environment
Conservation of EnergyConservation of Energy
Law of Conservation of EnergyLaw of Conservation of Energy
– Energy cannot be made or destroyed, but can Energy cannot be made or destroyed, but can only change in formonly change in form
Scientific TheoryScientific Theory
A scientific theory is an idea supported by A scientific theory is an idea supported by evidence over a period of timeevidence over a period of time
The Law of Conservation of Energy is a The Law of Conservation of Energy is a scientific theoryscientific theory
Matter and EnergyMatter and Energy
Matter can be changed into energyMatter can be changed into energy
Energy can be changed into matterEnergy can be changed into matter
– The total amount of matter and energy in the The total amount of matter and energy in the universe does not changeuniverse does not change
– This is explained by the equation:This is explained by the equation:
E=mcE=mc22
E=mcE=mc22
E – energyE – energy
m – matter or massm – matter or mass
c – speed of lightc – speed of light
WorkWork
Work equals force times distanceWork equals force times distance
WorkWork
Work is done when a force moves an Work is done when a force moves an object a certain distanceobject a certain distance
– If an object is not moved, no work is doneIf an object is not moved, no work is done
WorkWork
Energy is the ability to do workEnergy is the ability to do work
– However, energy can be used without doing However, energy can be used without doing workwork
WorkWork
For work to be done, the direction of the For work to be done, the direction of the applied force must be the same as the applied force must be the same as the direction of the motiondirection of the motion
Measuring WorkMeasuring Work
To measure work, you must know:To measure work, you must know:
– The force in NewtonsThe force in Newtons
– The distance in metersThe distance in meters
– Work can be measured in Newton-metersWork can be measured in Newton-meters(N-m)(N-m)
JoulesJoules
The metric unit of work is the Joule (J)The metric unit of work is the Joule (J)
– 1 J (Joule) = 1 N-m (Newton-meter)1 J (Joule) = 1 N-m (Newton-meter)
Measuring WorkMeasuring Work
When measuring work, you must measure When measuring work, you must measure the force applied in the direction of motionthe force applied in the direction of motion
PowerPower
Power is the amount of work done per unit Power is the amount of work done per unit of timeof time
Power is the rate at which work is donePower is the rate at which work is done
Power = work / timePower = work / time
Power = (force X distance) / timePower = (force X distance) / time
PowerPower
The metric unit of power is the Watt (W)The metric unit of power is the Watt (W)
– 1 Watt (W) = 1 Joule per second (J/sec)1 Watt (W) = 1 Joule per second (J/sec)1 W = 1 N-m/sec1 W = 1 N-m/sec
1 W = 1 J/sec1 W = 1 J/sec
PowerPower
Large amounts of power are measured in Large amounts of power are measured in kilowatts (kW)kilowatts (kW)
– 1 kW = 1000 W1 kW = 1000 W