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14.40. Set Up:
Energy is
calculate the heat energy
Q
produced in one hour. The mass
m
of water
that vaporizes is related to
Q
by
1.0 kg of water has a volume of 1.0 L.
Solve: (a)
each hour.
(b)
The number of bottles of water is
14.41. Set Up:
From Problem 14.40,
and
Convert the temperature change in
to
using that
Solve: (a)
so
(b)
A fever this high can be lethal (heat stroke).
14.42. Set Up:
Calculate
Q
for each mass of water and set their algebraic sum equal to zero. Let the water you add
have mass
m
. The 750 g of cold water has a temperature change of
and a heat flow
The mass
m
of water
has a temperature change of
and a heat flow
Solve:
so
and
14.43. Set Up:
For water,
Solve: (a)
says
(b)
Water has a much larger value of
c
so stores more heat for the same
(c)
If some of the heat went into the Styrofoam™ then more would have to come out of the metal and
c
would be
found to be greater. The value calculated in (a) would be too small.
Reflect:
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 Spring '07
 Shoberg
 Energy, Mass, Power, Heat

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