TEMPERATURE amp HEAT

AP Physics

TEMPERATUREA measure of the average kinetic energy of the

particles in a sample of matter expressed in terms of units or degrees designated on a standard scale

~American Heritage Dictionary

3 ScalesScale Boiling Point of

H2OFreezing Point of

H2OAbsolute

Zero

Fahrenheit

Celsius

Kelvin

THERMAL EQUILIBRIUMTwo systems are in thermal equilibrium if and only if

they have the same temperature

Two systems that are each in thermal equilibrium with a third system are in thermal equilibrium with each other

ZEROTH LAW OF THERMODYNAMICS

THERMAL EXPANSIONMost materials expand when

their temperature increases

Linear Expansion Expansion in one dimension

(usually the length) change in length is

proportional to the change in temperature

Material α (1oC)

Aluminum 24 x 10-

6

Brass amp Bronze

19 x 10-

6

Copper 17 x 10-

6

Steel 11 x 10-

6

Concrete 12 x 10-

6

EXPANSION OF RAILROAD TRACKS

A steel railroad track has a length of 30000 m when the temperature is 0oC What is its length on a hot day when the temperature is 40oC

α = 11 x 10-6 (oC)-1

JAMES JOULE AND HEATJames Joule discovered by various means that he could heat a body

of water by purely mechanical means

a) by lowering a weight and letting a paddle wheel stir the water

b) by passing electric current through a resistor

c) by compressing a piston immersed in the water

d) by friction from rubbing blocks together

He found that about 800 foot-pounds ( 1 kilo joule) of work could raise the temperature of one pound (45 kilograms) of water one Fahrenheit degree (055oC)

HEAT (Q)Energy that is transferred from one object or system

to another object or system as a result of a temperature difference

(The concept of heat only has meaning as energy in transit)

Heat flow is energy transfer

Units Joule (J) calorie (cal) Calorie (Cal) British thermal unit (Btu)

Unit Relations

Joules calories Calories Btu

1 0239 239 x 10-4

948 x 10-4

4186 1 0001 397 x 10-3

4186 1000 1 397

1055 252 0252 1

The calorie is defined as the amount of heat required to raise the temperature of 1 gram of water from 145oC to 155oC

One Btu is defined as the quantity of heat required to raise the temperature of 1 pound of water from 63oF to 64oF

TEMPERATUREA measure of the average kinetic energy of the

particles in a sample of matter expressed in terms of units or degrees designated on a standard scale

~American Heritage Dictionary

3 ScalesScale Boiling Point of

H2OFreezing Point of

H2OAbsolute

Zero

Fahrenheit

Celsius

Kelvin

THERMAL EQUILIBRIUMTwo systems are in thermal equilibrium if and only if

they have the same temperature

Two systems that are each in thermal equilibrium with a third system are in thermal equilibrium with each other

ZEROTH LAW OF THERMODYNAMICS

THERMAL EXPANSIONMost materials expand when

their temperature increases

Linear Expansion Expansion in one dimension

(usually the length) change in length is

proportional to the change in temperature

Material α (1oC)

Aluminum 24 x 10-

6

Brass amp Bronze

19 x 10-

6

Copper 17 x 10-

6

Steel 11 x 10-

6

Concrete 12 x 10-

6

EXPANSION OF RAILROAD TRACKS

A steel railroad track has a length of 30000 m when the temperature is 0oC What is its length on a hot day when the temperature is 40oC

α = 11 x 10-6 (oC)-1

JAMES JOULE AND HEATJames Joule discovered by various means that he could heat a body

of water by purely mechanical means

a) by lowering a weight and letting a paddle wheel stir the water

b) by passing electric current through a resistor

c) by compressing a piston immersed in the water

d) by friction from rubbing blocks together

He found that about 800 foot-pounds ( 1 kilo joule) of work could raise the temperature of one pound (45 kilograms) of water one Fahrenheit degree (055oC)

HEAT (Q)Energy that is transferred from one object or system

to another object or system as a result of a temperature difference

(The concept of heat only has meaning as energy in transit)

Heat flow is energy transfer

Units Joule (J) calorie (cal) Calorie (Cal) British thermal unit (Btu)

Unit Relations

Joules calories Calories Btu

1 0239 239 x 10-4

948 x 10-4

4186 1 0001 397 x 10-3

4186 1000 1 397

1055 252 0252 1

The calorie is defined as the amount of heat required to raise the temperature of 1 gram of water from 145oC to 155oC

One Btu is defined as the quantity of heat required to raise the temperature of 1 pound of water from 63oF to 64oF

THERMAL EQUILIBRIUMTwo systems are in thermal equilibrium if and only if

they have the same temperature

Two systems that are each in thermal equilibrium with a third system are in thermal equilibrium with each other

ZEROTH LAW OF THERMODYNAMICS

THERMAL EXPANSIONMost materials expand when

their temperature increases

Linear Expansion Expansion in one dimension

(usually the length) change in length is

proportional to the change in temperature

Material α (1oC)

Aluminum 24 x 10-

6

Brass amp Bronze

19 x 10-

6

Copper 17 x 10-

6

Steel 11 x 10-

6

Concrete 12 x 10-

6

EXPANSION OF RAILROAD TRACKS

A steel railroad track has a length of 30000 m when the temperature is 0oC What is its length on a hot day when the temperature is 40oC

α = 11 x 10-6 (oC)-1

JAMES JOULE AND HEATJames Joule discovered by various means that he could heat a body

of water by purely mechanical means

a) by lowering a weight and letting a paddle wheel stir the water

b) by passing electric current through a resistor

c) by compressing a piston immersed in the water

d) by friction from rubbing blocks together

He found that about 800 foot-pounds ( 1 kilo joule) of work could raise the temperature of one pound (45 kilograms) of water one Fahrenheit degree (055oC)

HEAT (Q)Energy that is transferred from one object or system

to another object or system as a result of a temperature difference

(The concept of heat only has meaning as energy in transit)

Heat flow is energy transfer

Units Joule (J) calorie (cal) Calorie (Cal) British thermal unit (Btu)

Unit Relations

Joules calories Calories Btu

1 0239 239 x 10-4

948 x 10-4

4186 1 0001 397 x 10-3

4186 1000 1 397

1055 252 0252 1

The calorie is defined as the amount of heat required to raise the temperature of 1 gram of water from 145oC to 155oC

One Btu is defined as the quantity of heat required to raise the temperature of 1 pound of water from 63oF to 64oF

THERMAL EXPANSIONMost materials expand when

their temperature increases

Linear Expansion Expansion in one dimension

(usually the length) change in length is

proportional to the change in temperature

Material α (1oC)

Aluminum 24 x 10-

6

Brass amp Bronze

19 x 10-

6

Copper 17 x 10-

6

Steel 11 x 10-

6

Concrete 12 x 10-

6

EXPANSION OF RAILROAD TRACKS

A steel railroad track has a length of 30000 m when the temperature is 0oC What is its length on a hot day when the temperature is 40oC

α = 11 x 10-6 (oC)-1

JAMES JOULE AND HEATJames Joule discovered by various means that he could heat a body

of water by purely mechanical means

a) by lowering a weight and letting a paddle wheel stir the water

b) by passing electric current through a resistor

c) by compressing a piston immersed in the water

d) by friction from rubbing blocks together

He found that about 800 foot-pounds ( 1 kilo joule) of work could raise the temperature of one pound (45 kilograms) of water one Fahrenheit degree (055oC)

HEAT (Q)Energy that is transferred from one object or system

to another object or system as a result of a temperature difference

(The concept of heat only has meaning as energy in transit)

Heat flow is energy transfer

Units Joule (J) calorie (cal) Calorie (Cal) British thermal unit (Btu)

Unit Relations

Joules calories Calories Btu

1 0239 239 x 10-4

948 x 10-4

4186 1 0001 397 x 10-3

4186 1000 1 397

1055 252 0252 1

The calorie is defined as the amount of heat required to raise the temperature of 1 gram of water from 145oC to 155oC

One Btu is defined as the quantity of heat required to raise the temperature of 1 pound of water from 63oF to 64oF

EXPANSION OF RAILROAD TRACKS

A steel railroad track has a length of 30000 m when the temperature is 0oC What is its length on a hot day when the temperature is 40oC

α = 11 x 10-6 (oC)-1

JAMES JOULE AND HEATJames Joule discovered by various means that he could heat a body

of water by purely mechanical means

a) by lowering a weight and letting a paddle wheel stir the water

b) by passing electric current through a resistor

c) by compressing a piston immersed in the water

d) by friction from rubbing blocks together

He found that about 800 foot-pounds ( 1 kilo joule) of work could raise the temperature of one pound (45 kilograms) of water one Fahrenheit degree (055oC)

HEAT (Q)Energy that is transferred from one object or system

to another object or system as a result of a temperature difference

(The concept of heat only has meaning as energy in transit)

Heat flow is energy transfer

Units Joule (J) calorie (cal) Calorie (Cal) British thermal unit (Btu)

Unit Relations

Joules calories Calories Btu

1 0239 239 x 10-4

948 x 10-4

4186 1 0001 397 x 10-3

4186 1000 1 397

1055 252 0252 1

The calorie is defined as the amount of heat required to raise the temperature of 1 gram of water from 145oC to 155oC

One Btu is defined as the quantity of heat required to raise the temperature of 1 pound of water from 63oF to 64oF

JAMES JOULE AND HEATJames Joule discovered by various means that he could heat a body

of water by purely mechanical means

a) by lowering a weight and letting a paddle wheel stir the water

b) by passing electric current through a resistor

c) by compressing a piston immersed in the water

d) by friction from rubbing blocks together

He found that about 800 foot-pounds ( 1 kilo joule) of work could raise the temperature of one pound (45 kilograms) of water one Fahrenheit degree (055oC)

HEAT (Q)Energy that is transferred from one object or system

to another object or system as a result of a temperature difference

(The concept of heat only has meaning as energy in transit)

Heat flow is energy transfer

Units Joule (J) calorie (cal) Calorie (Cal) British thermal unit (Btu)

Unit Relations

Joules calories Calories Btu

1 0239 239 x 10-4

948 x 10-4

4186 1 0001 397 x 10-3

4186 1000 1 397

1055 252 0252 1

The calorie is defined as the amount of heat required to raise the temperature of 1 gram of water from 145oC to 155oC

One Btu is defined as the quantity of heat required to raise the temperature of 1 pound of water from 63oF to 64oF

HEAT (Q)Energy that is transferred from one object or system

to another object or system as a result of a temperature difference

(The concept of heat only has meaning as energy in transit)

Heat flow is energy transfer

Units Joule (J) calorie (cal) Calorie (Cal) British thermal unit (Btu)

Unit Relations

Joules calories Calories Btu

1 0239 239 x 10-4

948 x 10-4

4186 1 0001 397 x 10-3

4186 1000 1 397

1055 252 0252 1

The calorie is defined as the amount of heat required to raise the temperature of 1 gram of water from 145oC to 155oC

One Btu is defined as the quantity of heat required to raise the temperature of 1 pound of water from 63oF to 64oF

SPECIFIC HEAT CAPACITYQuantity of heat needed to change the temperature of a system is

dependent on three things

1 The quantity of the temperature change

2 The mass of the system

3 The nature of the material

The amount of heat Q needed for a certain temperature change ΔT is proportional to the temperature change and to the mass m of substance being heated

DOWN WITH THE SICKNESS

Material c [J(kgK)]

Water 419 x 103

Ice (-25oC to 0oC)

201 x 103

Aluminum 091 x 103

Salt 088 x 103

Iron 047 x 103

Silver 023 x 103

During a bout with the flu an 80 kg man ran a fever of 20 Co His body temperature was 390oC (1022oF) instead of the normal 37oC Assuming that the human body is mostly water how much heat was required to raise his temperature by that amount

CIRCUITRY OVERLOADYou are an electric engineer designing an electronic circuit

element made of 23 mg of silicon The electric current through it adds energy at the rate of 74 mW (74 x 10-3 Js) If your design doesnrsquot allow for any heat transfer out of the element at what rate does its temperature increase The specific heat capacity of silicon is 705 J(kgK)

COOLING A HOT INGOTIngot - metal that is cast in the shape of a block for

convenient handling

A 00500 kg ingot of metal is heated to 2000oC and then dropped into a beaker containing 0400 kg of water that is initially at 200oC If the final equilibrium temperature of the mixed system is 224oC find the specific heat of the metal

PHASES OF MATTERThree familiar phases of matter include

1 Gases

2 Liquids

3 Solids

hellipbut there are more than those three includinghellip

plasmas superfluids supersolids Bose-Einstein condensates fermionic condensates liquid crystals strange matter and quark-gluon plasmas

PHASE CHANGESTransition from one phase of matter to another

What goes on during a phase changeAt a given pressure phase changes

1 usually occur at a definite temperature

2 heat is absorbed or released

3 there is a change in volume of the matter

4 there is a change in density of the matter

At this temperature and pressure both phases of matter can coexist this is called phase equilibrium

TYPES OF PHASE CHANGES

Phase Change Process Example Heat Required per unit

mass

Solid Liquid Metal gallium melts in your hand Latent Heat

of Fusion (Lf)Liquid Solid Water freezes

Liquid Gas Liquid Nitrogen boils at room temp

Latent Heat of

Vaporization (Lv)Gas Liquid Water vapor condenses

Solid GasDry Ice (CO2) sublimes to its gaseous phase at room

temp

Latent Heat of

Sublimation (Ls)Gas Solid Frost forms on cold

objects

To melt a mass m of material that has a heat of fusion Lf requires a heat Q given by

To freeze a mass m of material that has a heat of fusion Lf requires a heat Q given by

A CLOSER LOOK AT PHASE CHANGESTo cause a phase change energy must be absorbed or released

by the objectsystem During the phase change the heat energy does not change the temperature of the object

DO THE DEWA physics student wants to cool 025 kg of Mountain Dew (mostly

water and high fructose corn syrup) initially at 20oC by adding ice initially at -20oC How much ice should she add so that the final temperature will be 0oC with all the ice melted Assume that the heat capacity of the container may be neglected

HEAT TRANSFERThere are three mechanisms of heat transfer1 Radiation2 Convection3 Conduction

RADIATIONEnergy transfer through electromagnetic

radiation (fancy words for light)

Ex

CONVECTIONEnergy transfer of heat by the motion of

a mass of fluid

Ex

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

COOLING A HOT INGOTIngot - metal that is cast in the shape of a block for

convenient handling

A 00500 kg ingot of metal is heated to 2000oC and then dropped into a beaker containing 0400 kg of water that is initially at 200oC If the final equilibrium temperature of the mixed system is 224oC find the specific heat of the metal

PHASES OF MATTERThree familiar phases of matter include

1 Gases

2 Liquids

3 Solids

hellipbut there are more than those three includinghellip

plasmas superfluids supersolids Bose-Einstein condensates fermionic condensates liquid crystals strange matter and quark-gluon plasmas

PHASE CHANGESTransition from one phase of matter to another

What goes on during a phase changeAt a given pressure phase changes

1 usually occur at a definite temperature

2 heat is absorbed or released

3 there is a change in volume of the matter

4 there is a change in density of the matter

At this temperature and pressure both phases of matter can coexist this is called phase equilibrium

TYPES OF PHASE CHANGES

Phase Change Process Example Heat Required per unit

mass

Solid Liquid Metal gallium melts in your hand Latent Heat

of Fusion (Lf)Liquid Solid Water freezes

Liquid Gas Liquid Nitrogen boils at room temp

Latent Heat of

Vaporization (Lv)Gas Liquid Water vapor condenses

Solid GasDry Ice (CO2) sublimes to its gaseous phase at room

temp

Latent Heat of

Sublimation (Ls)Gas Solid Frost forms on cold

objects

To melt a mass m of material that has a heat of fusion Lf requires a heat Q given by

To freeze a mass m of material that has a heat of fusion Lf requires a heat Q given by

A CLOSER LOOK AT PHASE CHANGESTo cause a phase change energy must be absorbed or released

by the objectsystem During the phase change the heat energy does not change the temperature of the object

DO THE DEWA physics student wants to cool 025 kg of Mountain Dew (mostly

water and high fructose corn syrup) initially at 20oC by adding ice initially at -20oC How much ice should she add so that the final temperature will be 0oC with all the ice melted Assume that the heat capacity of the container may be neglected

HEAT TRANSFERThere are three mechanisms of heat transfer1 Radiation2 Convection3 Conduction

RADIATIONEnergy transfer through electromagnetic

radiation (fancy words for light)

Ex

CONVECTIONEnergy transfer of heat by the motion of

a mass of fluid

Ex

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

PHASES OF MATTERThree familiar phases of matter include

1 Gases

2 Liquids

3 Solids

hellipbut there are more than those three includinghellip

plasmas superfluids supersolids Bose-Einstein condensates fermionic condensates liquid crystals strange matter and quark-gluon plasmas

PHASE CHANGESTransition from one phase of matter to another

What goes on during a phase changeAt a given pressure phase changes

1 usually occur at a definite temperature

2 heat is absorbed or released

3 there is a change in volume of the matter

4 there is a change in density of the matter

At this temperature and pressure both phases of matter can coexist this is called phase equilibrium

TYPES OF PHASE CHANGES

Phase Change Process Example Heat Required per unit

mass

Solid Liquid Metal gallium melts in your hand Latent Heat

of Fusion (Lf)Liquid Solid Water freezes

Liquid Gas Liquid Nitrogen boils at room temp

Latent Heat of

Vaporization (Lv)Gas Liquid Water vapor condenses

Solid GasDry Ice (CO2) sublimes to its gaseous phase at room

temp

Latent Heat of

Sublimation (Ls)Gas Solid Frost forms on cold

objects

To melt a mass m of material that has a heat of fusion Lf requires a heat Q given by

To freeze a mass m of material that has a heat of fusion Lf requires a heat Q given by

A CLOSER LOOK AT PHASE CHANGESTo cause a phase change energy must be absorbed or released

by the objectsystem During the phase change the heat energy does not change the temperature of the object

DO THE DEWA physics student wants to cool 025 kg of Mountain Dew (mostly

water and high fructose corn syrup) initially at 20oC by adding ice initially at -20oC How much ice should she add so that the final temperature will be 0oC with all the ice melted Assume that the heat capacity of the container may be neglected

HEAT TRANSFERThere are three mechanisms of heat transfer1 Radiation2 Convection3 Conduction

RADIATIONEnergy transfer through electromagnetic

radiation (fancy words for light)

Ex

CONVECTIONEnergy transfer of heat by the motion of

a mass of fluid

Ex

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

PHASE CHANGESTransition from one phase of matter to another

What goes on during a phase changeAt a given pressure phase changes

1 usually occur at a definite temperature

2 heat is absorbed or released

3 there is a change in volume of the matter

4 there is a change in density of the matter

At this temperature and pressure both phases of matter can coexist this is called phase equilibrium

TYPES OF PHASE CHANGES

Phase Change Process Example Heat Required per unit

mass

Solid Liquid Metal gallium melts in your hand Latent Heat

of Fusion (Lf)Liquid Solid Water freezes

Liquid Gas Liquid Nitrogen boils at room temp

Latent Heat of

Vaporization (Lv)Gas Liquid Water vapor condenses

Solid GasDry Ice (CO2) sublimes to its gaseous phase at room

temp

Latent Heat of

Sublimation (Ls)Gas Solid Frost forms on cold

objects

To melt a mass m of material that has a heat of fusion Lf requires a heat Q given by

To freeze a mass m of material that has a heat of fusion Lf requires a heat Q given by

A CLOSER LOOK AT PHASE CHANGESTo cause a phase change energy must be absorbed or released

by the objectsystem During the phase change the heat energy does not change the temperature of the object

DO THE DEWA physics student wants to cool 025 kg of Mountain Dew (mostly

water and high fructose corn syrup) initially at 20oC by adding ice initially at -20oC How much ice should she add so that the final temperature will be 0oC with all the ice melted Assume that the heat capacity of the container may be neglected

HEAT TRANSFERThere are three mechanisms of heat transfer1 Radiation2 Convection3 Conduction

RADIATIONEnergy transfer through electromagnetic

radiation (fancy words for light)

Ex

CONVECTIONEnergy transfer of heat by the motion of

a mass of fluid

Ex

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

TYPES OF PHASE CHANGES

Phase Change Process Example Heat Required per unit

mass

Solid Liquid Metal gallium melts in your hand Latent Heat

of Fusion (Lf)Liquid Solid Water freezes

Liquid Gas Liquid Nitrogen boils at room temp

Latent Heat of

Vaporization (Lv)Gas Liquid Water vapor condenses

Solid GasDry Ice (CO2) sublimes to its gaseous phase at room

temp

Latent Heat of

Sublimation (Ls)Gas Solid Frost forms on cold

objects

To melt a mass m of material that has a heat of fusion Lf requires a heat Q given by

To freeze a mass m of material that has a heat of fusion Lf requires a heat Q given by

A CLOSER LOOK AT PHASE CHANGESTo cause a phase change energy must be absorbed or released

by the objectsystem During the phase change the heat energy does not change the temperature of the object

DO THE DEWA physics student wants to cool 025 kg of Mountain Dew (mostly

water and high fructose corn syrup) initially at 20oC by adding ice initially at -20oC How much ice should she add so that the final temperature will be 0oC with all the ice melted Assume that the heat capacity of the container may be neglected

HEAT TRANSFERThere are three mechanisms of heat transfer1 Radiation2 Convection3 Conduction

RADIATIONEnergy transfer through electromagnetic

radiation (fancy words for light)

Ex

CONVECTIONEnergy transfer of heat by the motion of

a mass of fluid

Ex

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

A CLOSER LOOK AT PHASE CHANGESTo cause a phase change energy must be absorbed or released

by the objectsystem During the phase change the heat energy does not change the temperature of the object

DO THE DEWA physics student wants to cool 025 kg of Mountain Dew (mostly

water and high fructose corn syrup) initially at 20oC by adding ice initially at -20oC How much ice should she add so that the final temperature will be 0oC with all the ice melted Assume that the heat capacity of the container may be neglected

HEAT TRANSFERThere are three mechanisms of heat transfer1 Radiation2 Convection3 Conduction

RADIATIONEnergy transfer through electromagnetic

radiation (fancy words for light)

Ex

CONVECTIONEnergy transfer of heat by the motion of

a mass of fluid

Ex

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

DO THE DEWA physics student wants to cool 025 kg of Mountain Dew (mostly

water and high fructose corn syrup) initially at 20oC by adding ice initially at -20oC How much ice should she add so that the final temperature will be 0oC with all the ice melted Assume that the heat capacity of the container may be neglected

HEAT TRANSFERThere are three mechanisms of heat transfer1 Radiation2 Convection3 Conduction

RADIATIONEnergy transfer through electromagnetic

radiation (fancy words for light)

Ex

CONVECTIONEnergy transfer of heat by the motion of

a mass of fluid

Ex

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

HEAT TRANSFERThere are three mechanisms of heat transfer1 Radiation2 Convection3 Conduction

RADIATIONEnergy transfer through electromagnetic

radiation (fancy words for light)

Ex

CONVECTIONEnergy transfer of heat by the motion of

a mass of fluid

Ex

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

RADIATIONEnergy transfer through electromagnetic

radiation (fancy words for light)

Ex

CONVECTIONEnergy transfer of heat by the motion of

a mass of fluid

Ex

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

CONVECTIONEnergy transfer of heat by the motion of

a mass of fluid

Ex

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

CONDUCTIONheat transfer through a material from regions of

higher temperatures to regions of lower temperatures

Good thermal conductors are metals because they have many free electrons

Ex

Rate of Heat TransferhellipHeat Current (H)

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

RATE OF HEAT TRANSFER (H)

The rate of heat transfer through a material with regions of varying temperatures is

proportional to the cross sectional area A proportional to the temperature difference ΔT inversely proportional to the distance between the regions L

The constant of proportionality is the thermal conductivity of the material k

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

COOLER CONDUCTIONThe StyrofoamTM box seen below is used to keep drinks cold at

a picnic (or wild beach party whatever suits your taste) The total area of the sides top and bottom is 080 m2 and the wall thickness is 20 cm The box is filled with ice and Root Beer keeping the inner surface at 0oC What is the rate of heat flow into the box if the temperature of the outside surface is 30oC How much ice melts in one day (24 hr)

Material k (W(mK)

Silver 406

Copper 385

StyrofoamT

M

001

Wood 012 ndash 004

Air 0024

CONDUCTION IN SERIESA steel bar 100 cm long is welded end to end to a copper

bar 200 cm long Each bar has a square cross section 200 cm on a side The free end of the steel bar is in contact with steam at 100oC and the free end of the copper bar is in contact with ice at 0oC Find the temperature at the junction of the two bars and the total rate of heat flow

Material k (W(mK)

Steel 502

Copper 385

• Temperature amp Heat
• Temperature
• Thermal Equilibrium
• Thermal Expansion
• Expansion of Railroad Tracks
• James Joule and Heat
• Heat (Q)
• Specific Heat Capacity
• Down with the Sickness
• Circuitry Overload
• Cooling a hot ingot
• Phases of Matter
• Phase Changes
• Types of Phase Changes
• A Closer look at Phase Changes
• DO The Dew
• Heat Transfer
• Radiation
• Convection
• Conduction
• Rate of Heat Transfer (H)
• Cooler Conduction
• Conduction In Series