Page 21 - FINAL DBS10012_HEAT TEMPERATURE 20102022 (2) (1)

EXAMPLE 1-2

1) Calculate the heat quantity needed to raise a temperature of 7 kg water as much
o
as 30 C. Specific heat capacity of water is 4200 J/kg C.
o

Solution:
Q = mc∆T

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o
= (7kg) (4200J/kg C) (30 C)
= 882 kJ

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2) Calculate the heat quantity needed to raise a temperature of 6 kg metal from 10 C to 80 C.

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Specific heat capacity of water is 0.38 kJ/kg C.

Solution:

Q = mc∆T
= (6 kg) (0.38kJ/kg C) (80 C – 10 C)
o
o
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= 159.6 kJ

3) To a 1 kg sample of wood 40 kJ of heat is added, and its temperature is found to

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o
rise from 20 C to 44 C. What is the specific heat capacity of the wood?

Solution:

Q = mc∆T

o
o
40 kJ = 1 kg x c x (44 C – 20 C)

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24 kg C (c) = 40 kJ

c = 40 kJ

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24 kg C

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= 1.67 kJ/kg C

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4) 42 kJ heat is used to raise water temperature from 20 C to 30 C. Determine the mass

o
of the water. For water, c water = 4.2 kJ/kg C.
Solution:
Q = mc∆T
42000 J = m x 4.2 x (30-20)

m = 42000 = 1 kg
42000

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