Chapter 10 Heat and Temperature. Temperature Page 324 Temperature is proportional to the average kinetic energy of an object.

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