p19_098.pdf

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Chapter 19 - 19.98

98. Let the initial water temperature be T wi and the initial thermometer temperature be T ti . Then, the

heat absorbed by the thermometer is equal (in magnitude) to the heat lost by the water:

c t m t ( T f −

T ti )= c w m w ( T wi −

T f ) .

We solve for the initial temperature of the water:

T wi =

c t m t ( T f −

T ti )

+ T f

c w m w

(0 . 0550 kg)(0 . 837 kJ / kg

K)(44 . 4

−

15 . 0) K

+44 . 4 ◦ C

(4 . 18 kJ / kg

C ◦ )(0 . 300 kg)

=45 . 5 ◦ C .