### TOPIC: Heat AIM: How is heat measured?

TOPIC: Heat
AIM: What is heat &
how is it measured?
• What you will learn:
1.Define temp.
2.Explain how thermal energy
and temp are related.
3.Calculate the change in
thermal energy of an object
due to temp change.
• Why is it important:
Cars, buses, trucks and airplanes
could not operate without
thermal energy.
What is kinetic energy?
•Review vocab:
•Kinetic energy: energy an
object has due to motion
• New Vocab
• Kinetic theory
• Kelvin
• Temp
• Thermal energy
• Heat
• Specific heat
Kinetic Theory of Matter
molecules that are
always in motion which
collide & transfer their
Kinetic Energy
• Molecules are always moving which
produces heat
•The more heat that is contained the
faster the molecules move
What are
molecules?
Molecules • Tiny
particles that
make up matter
• Example: 1 molecule of water =
H 2O
5
molecules
of water
• Molecules moving (have KE)
What is • Energy caused by
internal motion of
heat?
molecules
• Energy moves from
warm  cooler region
Temperature
•Measure of how
hot or cold
something is
•Measure of
average KE of
molecules
If heat is added to an object the
faster
molecules move ________,
which
increases the Kinetic Energy,
_________
which causes the temperature to
_________.
increase
• Low temp = slower moving
• High temp = fast moving
The average kinetic energy of the
particles in the soup is greater than the
average kinetic energy of the particles in
the ice cream.
70°F
70°F
The pail of water has fewer molecules in
it than the ocean does. Even though they
may be the same temperature, the pail of
water has less heat than the ocean.
Thermometer • For
measuring
temperature
• Tube filled with a
fluid such as
mercury
• Heated molecules move
faster and far apart
• Mercury expands & rises up
tube
• Cooled  molecules slow &
move closer together 
• Mercury contracts and
drops
Heated
Liquid level
rises
Cooled
Liquid level
drops
•Non-metric
temp scale
Fahrenheit
Scale
°F
• Water freezes = 32°F
• Water boils = 212°F
• Human body temp = 98.6°F
Celsius
Scale
°C
•Metric scale
• Water freezes = 0°C
• Water boils = 100°C
• Human body temp = 37°C
Kelvin •Metric scale
scale •Units = Kelvins (K)
• Absolute Zero = 0K
• (coldest temp = when
molecules stop moving)
Conversions
°C  K •Celsius + 273K
K  °C •Kelvin - 273
Example:
56°C = ? K
•56 + 273 =
•329K
Example
400K ? °C
•400 – 273 =
•127 °C
Changing
Temp
• Increasing  heat
• Decreasing  heat
being REMOVED
How is
• CALORIES
heat
• unit of heat
measured?
• 1 calorie = 4.184 J
• Amount of heat
needed to raise the
temp of 1g of water
1°C
1000 calories (1 kilocalorie) = 1 food
Calorie
Your body uses the calories in food for heat and energy. Some
foods contain more calories than others, and therefore
provide your body with a concentration of energy. Foods that
are high in calories contain large amounts of chemical energy,
often more than your body can properly break down and use.
What's left over is often stored as fat. That's why people on
diets avoid foods that are high in calories.
TOPIC: Heat
AIM: What is
thermal expansion?
Thermal • Expansion (increase
Expansion in size) of a
substance caused by
heat
• Temp increases 
molecules move
faster & farther
apart
• Examples:
• 1. The rising of mercury/
alcohol in a thermometer
• 2.
• Hot air balloons rise
because heated air
expands
When both ball and ring are at room
temperature, the ball fits through the
ring.
When the ball is heated, it no longer fits
due to thermal expansion.
Spaces between the joints allow the
metals in the bridge to expand.
Summary:
• Recap lesson