NS 3310 – Physical NS 3310 – Physical Science StudiesScience Studies

Chapter 4 – Heat and Chapter 4 – Heat and TemperatureTemperature

Key QuestionsKey Questions What is heat? What is thermal energy? What is What is heat? What is thermal energy? What is

temperature? Is there a difference?temperature? Is there a difference?

How does heat move around?How does heat move around?

Why do some things feel hot and others cold?Why do some things feel hot and others cold?

How do substances change their state of matter? How do substances change their state of matter? How is heat involved?How is heat involved?

What are the laws of thermodynamics?What are the laws of thermodynamics?

What is entropy?What is entropy?

Kinetic Energy of MoleculesKinetic Energy of Molecules

SolidsSolids

FluidsFluids

– LiquidsLiquids

– GasesGases

– PlasmasPlasmas

TemperatureTemperature

Temperature measures the kinetic Temperature measures the kinetic energy of molecules (this is external energy of molecules (this is external energy)energy)

FahrenheitFahrenheit

CelsiusCelsius

Kelvin (absolute zero)Kelvin (absolute zero)

Thermal EnergyThermal Energy

Thermal energy is the internal Thermal energy is the internal energy of a moleculeenergy of a molecule

Heat is a measure of the internal Heat is a measure of the internal energy that has been absorbed or energy that has been absorbed or transferred from one body to anothertransferred from one body to another

Heat is measured in calories (c) or Heat is measured in calories (c) or British Thermal Units (BTUs)British Thermal Units (BTUs)

Specific Heat and Latent Specific Heat and Latent HeatHeat

Specific heat changes the temperature of an Specific heat changes the temperature of an objectobject

Latent heat changes the phase of the Latent heat changes the phase of the materialmaterial

For example: Ice to Water to SteamFor example: Ice to Water to Steam

Phase TransitionsPhase Transitions

Latent Heat of Fusion / MeltingLatent Heat of Fusion / Melting

Latent Heat of Latent Heat of

Vaporization / Vaporization /

CondensationCondensation

Relative HumidityRelative Humidity

Heat FlowHeat Flow

RadiationRadiation

ConductionConduction

ConvectionConvection

ThermodynamicsThermodynamics The First Law of ThermodynamicsThe First Law of Thermodynamics

– Applied Law of Energy ConservationApplied Law of Energy Conservation W = J(QW = J(QHH – Q – QLL))

The Second Law of The Second Law of ThermodynamicsThermodynamics

– Heat always flows from an areaHeat always flows from an area of higher concentration to anof higher concentration to an area of lower concentrationarea of lower concentration

EntropyEntropy

Perpetual Motion Machine?Perpetual Motion Machine?

Perpetual Motion MachinesPerpetual Motion Machines

Free EnergyFree Energy

Other ScamsOther Scams

Why Should We Worry About Why Should We Worry About Pseudoscience?Pseudoscience?

Key ConceptsKey Concepts Thermal energy is the internal and external Thermal energy is the internal and external

energy of atoms.energy of atoms. Heat is the transfer of thermal of energy between Heat is the transfer of thermal of energy between

atoms.atoms. Temperature is a measurement of the kinetic Temperature is a measurement of the kinetic

energy of molecules.energy of molecules. Adding heat energy to substances makes their Adding heat energy to substances makes their

temperature rise (specific heat).temperature rise (specific heat). To change the state of a substance requires even To change the state of a substance requires even

more heat (latent heat).more heat (latent heat). Heat can be transferred by radiation, conduction Heat can be transferred by radiation, conduction

and convection.and convection. Entropy describes the total energy of a system Entropy describes the total energy of a system

and tells us that we cannot get more energy out and tells us that we cannot get more energy out of a system than we put into it.of a system than we put into it.