Specific Heat

76

Specific Heat

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77

Specific Heat

You reach for a slice of pizza fresh from the hot oven. You take a
bite and the crust is nice and warm but when the sauce reaches
your tongue it burns!

If the sauce and crust were
at the same temperature,
why do you think the sauce
burned your tongue but the
crust did not?

78

The sauce required more thermal energy to reach the same temperature
as the crust because it had a higher specific heat capacity than the
crust.

Specific Heat

The sauce transferred more thermal energy to your tongue raising
your tongue's temperature.

But why did the sauce have more thermal energy than the crust? Click
HERE for the answer.

79

Specific Heat

Specific heat describes the amount of energy in Joules (J)
needed to raise the temperature of 1 kg of a substance by 1°C.

table: electron9.phys.utk.edu

Different substances have different specific heat capacities.
What do those values tell you about the substance?

80

Specific Heat

Differences in specific heat require different amounts of energy
for the same change in temperature.

1kg
It takes about 800 Joules of
energy to raise the
temperature of 1 kg of rock
by 1°C.

81

1kg

Specific Heat

It takes about 1,700 Joules of energy to raise the temperature of 1 kg
of wood by 1°C.

Which has the
higher specific
heat capacity, the
rock or the wood?

82

lowest specific heat

specific heat is in between

highest specific heat

temperature will be in between

highest temperature

lowest temperature

lowest specific heat

specific heat is in between

highest specific heat

Specific Heat

What happens if the same amount of thermal energy is transferred
to substances of the same mass but different specific heats?

For example, if equal
masses of water, sand and
air each recieve 1000 Joules
of energy how do their
temperatures compare?

Click the picture
for the answer.

The substance with a lower specific heat will heat up way faster

than the substance with a higher specific heat. (higher = slower to heat)

Multiple Choice

Specific heat describes the energy needed to raise the
temperature of 1kg of a substance by 1°C.

• True

• False

84

30 Which substance requires the least amount of energy to
change its temperature by the same amount?

A 1 kg of ice

B 1 kg of lead

C 1 kg of water

D 1 kg of copper

table: electron9.phys.utk.edu

Answer

lowest specific heat so easiest to heat

Multiple Choice

Which substance requires the least amount of energy to
change its temperature by the same amount?

• 1 kg of ice

• 1 kg of water

• 1 kg of lead

• 1 kg of copper

Multiple Choice

Exactly 200 Joules of thermal energy are transferred to
the following substances. Which undergoes the least
amount of temperature change?

• 1 kg of ice

• 1 kg of water

• 1 kg of lead

• 1 kg of copper

85

31 Exactly 200 Joules of thermal energy are transferred to
the following substances. Which undergoes the least
amount of temperature change?

A 1 kg of water

B 1 kg of copper

C 1 kg of iron

D 1 kg of aluminum

table: electron9.phys.utk.edu

Answer

B 1kg of water
Since it has the highest heat
capacity, it requires a lot more
energy to change its temperature by
the same amount.

highest specific heat =takes longest to change

86

Specific Heat

Identical substances with the same mass and the same specific
heat will undergo different temperature changes if they receive
different amounts of thermal energy

.

Use a red marker tool to illustrate on the thermometers the
differences in water temperature between the two flasks of water.

87

Specific Heat

Identical substances with different masses and the same
specific heat will undergo different temperature changes if they
recieve the same amount of thermal energy.

Use a red marker tool to illustrate on the thermometers the
differences in temperature between the two rocks.

Dropdown

Suppose two identical rocks of the same mass and same
specific heat are heated differently. How could you

Select answer

Multiple Choice

Suppose two identical rocks of different masses are
heated. After they each receive 200 Joules of thermal
energy. Rock "A" has a hotter temperature than rock "B".
Which rock is more massive?

• Rock A

• Rock B

89

33 Suppose two identical rocks of different masses are
heated. After they each receive 200 Joules of thermal
energy. Rock "A" has a hotter temperature than rock "B".
Which rock is more massive?

A

B

Rock

Rock

Answer

If rock A was hotter, that means

it was easier to heat up so it was

the smaller rock. This makes B

the bigger rock which takes longer

to heat.

90

Temperature Changes

To summarize, the temperature changes a substance undergoes:

Are inversely proportional to the specific heat of the substance

higher specific heat smaller temperature change

lower specific heat
greater temperature change

91

Are directly proportional to the amount of energy transferred
to the substance.

Temperature Changes

More energy greater temperature
change
less energy
smaller temperature change

92

Are inversely proportional to the mass of the substance

1kg

2kg

Temperature Changes

more mass smaller temperature change

less mass
greater temperature change

Multiple Select

What three quantities does the temperature change of an
object depend on?

• Objects density

• the amount of energy transferred to it

• Objects mass

• Objects specific heat

93

34 What three quantities does the temperature change of an
object depend on?

A the object's density

B the amount of energy transferred to it

C the object's mass

D the object's specific heat

Answer

All except the object's density.

Multiple Choice

One hundred Joules of thermal energy are added to the
following objects. Which undergoes the greatest
temperature change?

• 1 kg of aluminum

• 1 kg of water

• 3 kg of aluminum

• 3 kg of water

94

35 One hundred Joules of thermal energy are added to the
following objects. Which undergoes the greatest
temperature change?

A 1 kg of aluminum

B 3 kg of aluminum

C 1 kg of water

D 3 kg of water

table: electron9.phys.utk.edu

Answer

A

greatest temp change should be
the smallest mass AND smallest

specific heat since it's the easiest
to heat

95

Finding Temperature Change

TE

∆T =
mc

Thermal energy
(Joules, J)

mass
(kilograms, kg)

specific heat capacity
(Joules/°C∙kg)

change in
temperature
(°C)

Consistent with these relationships is the following equation for
change in temperature.

96

Finding Temperature Change

Try using the equation for the following.

How much thermal energy must be added to 130 kg of bath water
to change its temperature from 33°C to 37°C? The specific heat
of water is 4186 J/°C∙kg.

Answer

Multiple Choice

A 0.03kg silver spoon with a specific heat of about 300 J/
°C∙kg is placed into a cup of soup. The soup transfers 90
J of thermal energy to the spoon. What is the change in
the spoon's temperature in °C?

• 10 degrees

• 5 degrees

• 15 degrees

97

36 A 0.03kg silver spoon with a specific heat of about 300 J/
°C∙kg is placed into a cup of soup. The soup transfers 90
J of thermal energy to the spoon. What is the change in
the spoon's temperature in °C?

Answer

Multiple Choice

You want to cool 0.35 kg of water from room temp 20°C
to 5°C. How much thermal energy must be removed from
the water? Water has a specific heat of 4186 J/°C∙kg.

• 17982.5J

• 23982.5J

• 21976.5J

• 25982.5J

98

37 You want to cool 0.35 kg of water from room temp 20°C
to 5°C. How much thermal energy must be removed from
the water? Water has a specific heat of 4186 J/°C∙kg.

Answer

Multiple Choice

A 0.20 kg aluminum baking pan is placed in an oven and
absorbs 20,000J of thermal energy. If the baking pan had
a starting temperature of 20°C, what is its temperature
after being heated? The specific heat of aluminum is
900J/°C∙kg.

• 100 degrees

• 200 degrees

• 300 degrees

• 111.1 degrees

99

38 A 0.20 kg aluminum baking pan is placed in an oven and
absorbs 20,000J of thermal energy. If the baking pan had
a starting temperature of 20°C, what is its temperature
after being heated? The specific heat of aluminum is
900J/°C∙kg.

Answer

131.1°C

If you use the equation to solve for
∆T, you get about 111.1°C. Since the
pan started at 20°C then its final
temperature will be 20°C plus
111.1°C.

*if it started at 20o and

changed 111.1o, then
it's final temperature

should be 131.1o C