Post on 17-Jan-2018
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Transferring Thermal Energy
I Transfer of Energy
A Conduction-transfer of energy by direct contact
1 Faster moving particles of one substance come into contact with slower moving molecules of another substance
2 Conduction can take place in solids liquids amp gases
3 It is more likely to take place in solids
4 Metals are especially good conductors
B Convection-transfer of energy in a fluid by the movement of the heated particles
1 Any material that can flow is considered a fluidfluid
2 Heated particles collide with each other and transfer their energy
3 As particles move faster they tend to be farther apart
Offshore convection currents
Convection currents form by fluids heating up rising cooling off falling
C Radiation-the transfer of energy by electromagnetic waves
D Insulators- materials that slows heat flow
1 Metals are typically poor insulators
2 Gases are very good insulators
3 Some types of insulators use pockets of air to help keep heat from flowing
A Specific Heat-the amount of heat that is needed to raise the temp of 1kg of some material by 1degC (or 1K)
II Specific Heat
Table 1 pg 432
1 Specific heat is measured in JkgmiddotK OR JgmiddotordmC
2 Water is a good coolant because it has a high specific heat
Specific Heat Problem 1
How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the waterrsquos temperature from 250C to 370C
tCmQ Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
Specific Heat Problem 2
Identify an unknown substance with a mass of 0455 kg that absorbs 633 x 103J in which a temperature change of 1550C is observed
Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
tmQc
Practice Pg 434 ndash Questions 1 ndash 6
2 Conduction can take place in solids liquids amp gases
3 It is more likely to take place in solids
4 Metals are especially good conductors
B Convection-transfer of energy in a fluid by the movement of the heated particles
1 Any material that can flow is considered a fluidfluid
2 Heated particles collide with each other and transfer their energy
3 As particles move faster they tend to be farther apart
Offshore convection currents
Convection currents form by fluids heating up rising cooling off falling
C Radiation-the transfer of energy by electromagnetic waves
D Insulators- materials that slows heat flow
1 Metals are typically poor insulators
2 Gases are very good insulators
3 Some types of insulators use pockets of air to help keep heat from flowing
A Specific Heat-the amount of heat that is needed to raise the temp of 1kg of some material by 1degC (or 1K)
II Specific Heat
Table 1 pg 432
1 Specific heat is measured in JkgmiddotK OR JgmiddotordmC
2 Water is a good coolant because it has a high specific heat
Specific Heat Problem 1
How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the waterrsquos temperature from 250C to 370C
tCmQ Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
Specific Heat Problem 2
Identify an unknown substance with a mass of 0455 kg that absorbs 633 x 103J in which a temperature change of 1550C is observed
Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
tmQc
Practice Pg 434 ndash Questions 1 ndash 6
Offshore convection currents
Convection currents form by fluids heating up rising cooling off falling
C Radiation-the transfer of energy by electromagnetic waves
D Insulators- materials that slows heat flow
1 Metals are typically poor insulators
2 Gases are very good insulators
3 Some types of insulators use pockets of air to help keep heat from flowing
A Specific Heat-the amount of heat that is needed to raise the temp of 1kg of some material by 1degC (or 1K)
II Specific Heat
Table 1 pg 432
1 Specific heat is measured in JkgmiddotK OR JgmiddotordmC
2 Water is a good coolant because it has a high specific heat
Specific Heat Problem 1
How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the waterrsquos temperature from 250C to 370C
tCmQ Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
Specific Heat Problem 2
Identify an unknown substance with a mass of 0455 kg that absorbs 633 x 103J in which a temperature change of 1550C is observed
Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
tmQc
Practice Pg 434 ndash Questions 1 ndash 6
C Radiation-the transfer of energy by electromagnetic waves
D Insulators- materials that slows heat flow
1 Metals are typically poor insulators
2 Gases are very good insulators
3 Some types of insulators use pockets of air to help keep heat from flowing
A Specific Heat-the amount of heat that is needed to raise the temp of 1kg of some material by 1degC (or 1K)
II Specific Heat
Table 1 pg 432
1 Specific heat is measured in JkgmiddotK OR JgmiddotordmC
2 Water is a good coolant because it has a high specific heat
Specific Heat Problem 1
How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the waterrsquos temperature from 250C to 370C
tCmQ Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
Specific Heat Problem 2
Identify an unknown substance with a mass of 0455 kg that absorbs 633 x 103J in which a temperature change of 1550C is observed
Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
tmQc
Practice Pg 434 ndash Questions 1 ndash 6
D Insulators- materials that slows heat flow
1 Metals are typically poor insulators
2 Gases are very good insulators
3 Some types of insulators use pockets of air to help keep heat from flowing
A Specific Heat-the amount of heat that is needed to raise the temp of 1kg of some material by 1degC (or 1K)
II Specific Heat
Table 1 pg 432
1 Specific heat is measured in JkgmiddotK OR JgmiddotordmC
2 Water is a good coolant because it has a high specific heat
Specific Heat Problem 1
How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the waterrsquos temperature from 250C to 370C
tCmQ Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
Specific Heat Problem 2
Identify an unknown substance with a mass of 0455 kg that absorbs 633 x 103J in which a temperature change of 1550C is observed
Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
tmQc
Practice Pg 434 ndash Questions 1 ndash 6
A Specific Heat-the amount of heat that is needed to raise the temp of 1kg of some material by 1degC (or 1K)
II Specific Heat
Table 1 pg 432
1 Specific heat is measured in JkgmiddotK OR JgmiddotordmC
2 Water is a good coolant because it has a high specific heat
Specific Heat Problem 1
How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the waterrsquos temperature from 250C to 370C
tCmQ Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
Specific Heat Problem 2
Identify an unknown substance with a mass of 0455 kg that absorbs 633 x 103J in which a temperature change of 1550C is observed
Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
tmQc
Practice Pg 434 ndash Questions 1 ndash 6
Specific Heat Problem 1
How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the waterrsquos temperature from 250C to 370C
tCmQ Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
Specific Heat Problem 2
Identify an unknown substance with a mass of 0455 kg that absorbs 633 x 103J in which a temperature change of 1550C is observed
Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
tmQc
Practice Pg 434 ndash Questions 1 ndash 6
Specific Heat Problem 2
Identify an unknown substance with a mass of 0455 kg that absorbs 633 x 103J in which a temperature change of 1550C is observed
Symbol Meaning Unit
Q Energy Joules (J)
t change in temperature
ordmC
m mass Grams(g) OR kilograms(kg)
c specific heat JkgK OR JgordmC
tmQc
Practice Pg 434 ndash Questions 1 ndash 6
Practice Pg 434 ndash Questions 1 ndash 6