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Chapter 10Chapter 10
Heat and Heat and TemperatureTemperature
TemperatureTemperature
Page 324Page 324
Temperature is proportional Temperature is proportional to the average kinetic to the average kinetic energy of an objectenergy of an object
Measuring TempMeasuring Temp
ThermometersThermometers–Page 325Page 325Based on the principle that Based on the principle that most objects expand when most objects expand when their temperature increasestheir temperature increases
Measuring TempMeasuring Temp
Common ScalesCommon Scales
–CelsiusCelsius
–FahrenheitFahrenheit
–Kelvin – absolute zeroKelvin – absolute zero
Energy TransferEnergy Transfer
Always from higher temp to Always from higher temp to lower templower temp
Heat – page 330Heat – page 330
Dr. Carlson Dr. Carlson ThermodynamicsThermodynamics
Methods of Energy Methods of Energy TransferTransfer
3 ways3 ways
–ConductionConduction
–ConvectionConvection
–RadiationRadiation
ConductionConduction
Page 332Page 332
Involves objects in direct Involves objects in direct contactcontact
Example: metal fork that Example: metal fork that holds marshmallow holds marshmallow
ConvectionConvection
Page 332Page 332Movement of warm fluids – Movement of warm fluids – liquid or gasliquid or gasConvection CurrentConvection CurrentExample: warm air around Example: warm air around the campfirethe campfire
RadiationRadiation
Page 333Page 333
Does not require physical Does not require physical contact between objectscontact between objects
Example: heat you feel when Example: heat you feel when you stand near the campfireyou stand near the campfire
ConductorConductor
Page 334Page 334
What makes a good What makes a good conductor? conductor?
Metals better than non-Metals better than non-metalsmetals
InsulatorsInsulators
Page 335Page 335
Slow transfer of energy as Slow transfer of energy as heatheat
Example: Example:
–wooden spoonwooden spoon
Specific HeatSpecific Heat
Page 336Page 336
Characteristic physical Characteristic physical propertyproperty
Ratio can be used to predict Ratio can be used to predict larger changes for masses larger changes for masses other than 1 kgother than 1 kg
Using HeatUsing Heat
Machines can transfer Machines can transfer energy as heat from one energy as heat from one place to anotherplace to another
Examples? Examples?
–Air Con, Fridge, Air Con, Fridge,
Using HeatUsing Heat
Conservation of EnergyConservation of Energy
Energy moves from high Energy moves from high temp to lower temptemp to lower temp
Air ConditionerAir Conditioner
Removes energy as heat Removes energy as heat from the warm airfrom the warm air
Transfers energy to air Transfers energy to air outside the roomoutside the room
Cooling SystemCooling System
Page 343Page 343
Often use evaporation and Often use evaporation and condensation condensation
Refrigerant – page 344Refrigerant – page 344
Cooling SystemCooling System
Liquid – Gas - LiquidLiquid – Gas - Liquid
Changes of state always Changes of state always transfer lots of energytransfer lots of energy
Heating SystemsHeating Systems
Page 340Page 340
Transfers heat from outside Transfers heat from outside to insideto inside
Need a source of energyNeed a source of energy
Heating SystemsHeating Systems
Furnace or solar energy can Furnace or solar energy can be used to heat air or waterbe used to heat air or waterWhich can be pumped through Which can be pumped through a building to transfer energy a building to transfer energy and increase temperatureand increase temperature
Usable EnergyUsable Energy
Some is lost through Some is lost through conduction and radiationconduction and radiation
Usable energy decreasesUsable energy decreases
Insulation can decrease Insulation can decrease lossloss
