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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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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