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Chapter 1
Basics of Heat Transfer
Review Problems
1121
Cold water is to be heated in a 1200W teapot. The time needed to heat the water is to be
determined.
Assumptions
1
Steady operating conditions exist.
2
Thermal properties of the teapot and the water are
constant.
3
Heat loss from the teapot is negligible.
Properties
The average specific heats are given to be
0.6 kJ/kg.
°
C for the teapot and 4.18 kJ/kg.
°
C for
water.
Analysis
We take the teapot and the water in it as our system that is a
closed system (fixed mass). The energy balance in this case can be
expressed as
EE
E
EU
U
U
in
out
system
in
system
water
tea pot
−=
==
+
Δ
ΔΔ
Δ
Then the amount of energy needed to raise the temperature of water
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This note was uploaded on 01/14/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.
 Fall '10
 Dr.DanielArenas
 Thermodynamics, Mass, Heat

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