1 thermodynamics if there was a thermometer attached to the rubber band, what would you observe?
TRANSCRIPT
1
Thermodynamics
If there was a thermometer attached to the rubber band, what would you observe?
2
Thermodynamics
If there was a thermometer attached to the rubber band, what would you observe?
The temperature goes up
3
Thermodynamics
If there was a thermometer attached to the rubber band, what would you observe?
The temperature goes up
∆Q α ∆T
∆Q is the heat involved
Part 2, A: THERMODYNAMICS
HEAT
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Units
The unit on heat should be Joules, but oftenpeople use the calorie, or kilocalorie.
1 kcal = amount of heat required to raise 1 kg of water by 1 degree Celcius.
1 kilocal = 4.2 kilojoules4
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Thermodynamics
Heat
∆Q α ∆T
6
Thermodynamics
Heat
∆Q α ∆T
7
Thermodynamics
Heat
∆Q α ∆T or ∆Q = (slope) m ∆T
∆Q
m∆T
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Thermodynamics
Heat
∆Q α ∆T or ∆Q = (slope) m ∆T
NOTE: Equal masses
Iron
Water
m∆T
∆Q
Part 2, A: THERMODYNAMICS
HEAT
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4.2 kJ = amount of heat required to raise 1 kg of water by 1 degree Celcius.
Therefore, for water the slope is
4.2kJ
kg- Co9
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Thermodynamics
Heat
∆Q = (slope) m ∆T
The slope of this graph is called the specific heat capacity. For
water, the specific heat capacity is
4.2 kj/kg-oC
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Thermodynamics
Heat
∆Q = (4.2 kj/kg-oC ) m ∆T
How much heat is required to raise the temperature of 10 kg of water by 20 oC?
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Thermodynamics
Heat
∆Q = (4.2 kj/kg-oC ) m ∆T
How much heat is required to raise the temperature of 10 kg of water by 20 oC?
Heat = (4.2 kj/kg-oC ) (10 kg) (20 oC)= 840 kj
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Thermodynamics
Heat
∆Q = (slope) m ∆T
NOTE: Equal masses
Clay, Marble
Water∆Q
m∆T
Part 2, A: THERMODYNAMICS
HEAT
31
Question: Water has a high specific heatcapacity. When heat is added or removedfrom water, will this produce a relativelylarge or small change in temperature forthe water as compared to, for example,clay?
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15
Thermodynamics
Heat
∆Q = (slope) m ∆T
NOTE: Equal masses
Clay, Marble
Water∆Q
m∆T
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Thermodynamics
Heat
∆Q = (slope) m ∆T
NOTE: Equal masses
Clay, Marble
Water∆Q
m∆T
17
Thermodynamics
Heat
∆Q = (slope) m ∆T
NOTE: Equal masses
Clay, Marble
Water∆Q
m∆T
18
Thermodynamics
Heat
∆Q = (slope) m ∆T
NOTE: Equal masses
Clay, Marble
Water∆Q
m∆TSmall change Large change
Part 2, A: THERMODYNAMICS 31
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Thermodynamics
Heat
∆Q = (slope) m ∆T
The variation in temperature between day and night on mars can be as much as 150 degree Fahrenheit, while the variation in temperature on the earth is far smaller. Why?
Part 2, A: THERMODYNAMICS 31
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