Potential and Kinetic EnergyPotential and Kinetic Energy

Work and EnergyWork and EnergyWork = force x Work = force x distancedistance

Work is only done Work is only done when an object when an object changes positionchanges position

Expressed in joulesExpressed in joules

Energy = the ability to do workEnergy = the ability to do work

Energy can be present in any Energy can be present in any object at any timeobject at any time

Can only be observed when Can only be observed when energy is being transferred energy is being transferred from one object/system to from one object/system to anotheranother

Amount of energy can be Amount of energy can be measured by how much work measured by how much work is doneis done

Expressed in joulesExpressed in joules

How is all energy divided?How is all energy divided?

PotentialEnergy

KineticEnergy

All Energy

GravitationPotentialEnergy

ElasticPotentialEnergy

ChemicalPotentialEnergy

What is Potential Energy?What is Potential Energy?

o Energy that is Energy that is stored and waiting stored and waiting to be used laterto be used later

What is Gravitational Potential What is Gravitational Potential Energy?Energy?

o Potential energy Potential energy due to an due to an object’s positionobject’s position

o P.E. = mass xP.E. = mass x gravity x gravity x

heightheighto PE = mghPE = mgh

What is Elastic Potential What is Elastic Potential Energy?Energy?

o Potential energy due compression Potential energy due compression or expansion of an elastic object.or expansion of an elastic object.

Notice the ball compressingand expanding

More Examples of Elastic More Examples of Elastic Potential EnergyPotential Energy

What is Chemical Potential What is Chemical Potential Energy?Energy?

o Potential energy Potential energy stored within the stored within the chemical bonds chemical bonds of an objectof an object

Another Example of Another Example of Chemical Potential EnergyChemical Potential Energy

What is Kinetic Energy?What is Kinetic Energy?

KE = ½ m

v2

o Energy an object has Energy an object has due to its motiondue to its motion

o K.E. = .5 x mass x K.E. = .5 x mass x speedspeed22

Law of Conservation of Law of Conservation of EnergyEnergy

Energy cannot be created or Energy cannot be created or destroyeddestroyed

Energy changes form Energy changes form

It’s transferredIt’s transferred

Total energy in a Total energy in a

system remains system remains

the samethe same

Energy SystemsEnergy Systems

ClosedClosed – energy being transferred in and – energy being transferred in and out is minimal (can be ignored)out is minimal (can be ignored)

OpenOpen – exchange energy with space – exchange energy with space around themaround them

Energy TransferEnergy Transfer

o KE is transferred into PEKE is transferred into PEo PE is transferred into KEPE is transferred into KE

Notice that the “total” Notice that the “total” energy in the system energy in the system stays the samestays the same

Energy TransferEnergy Transfer

Wylie Coyote and Roderunner Wylie Coyote and Roderunner CartoonsCartoons

You try!You try!

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