 Matter contains thermal energy, not heat.
 Heat is the thermal energy in transit.
 Heat is the thermal energy transferred from one object to
another due to a temperature difference.
 Heat is the to the total kinetic energy of the atoms or molecules.
 Heat is measured in joules
 When you strike a nail with a hammer, it
becomes warm. Why?
 When you put a flame to a liquid, the
liquid becomes warmer as its molecules
move faster. Why?
 Temperature, the degree of “hotness” or
“coldness” of an object.
 Temperature is the to the average (NOT total) kinetic
energy of the atoms or molecules making it up.
- The scale most often used
world-wide is the Celsius
thermometer, where a zero
(0) is assigned to the
temperature at which water
freezes, and 100 is assigned
to the temperature at which
water boils (at standard
atmospheric pressure).
- In the U.S., the number 32 is traditionally
assigned to the temperature at which water
freezes, and the number 212 is the temperature at
which water boils. This is called the Fahrenheit scale.
- The absolute temperature
scale is called the Kelvin
scale. Absolute zero is 0
K. The melting point of
ice is 273 K, and the
boiling point of water is
373 K. There are no
negative numbers on the
Kelvin scale.
- Here’s the part you all LOVE to hate:
-How to convert from one scale to the other.
Fahrenheit to Celsius
Celsius to Kelvin
Celsius to Fahrenheit
Kelvin to Celsius
Here's a trick for converting Celsius to Fahrenheit in your head:
1) double the Celsius temperature
2) subtract one tenth of this value
3) add 32
EXAMPLE: let's use 30 degrees C as an example.
1) double the Celsius temperature (2 x 30 = 60)
2) subtract one tenth of this value (60 - 6 = 54)
3) add 32 (54 + 32 = 86 degrees F)
- In contrast to high temperatures, there is a definite limit
at the opposite end of the scale, called absolute zero.
Heat capacity as the amount of energy needed to change
the temperature of a material by one degree.
Sample Problem
How much heat is needed to raise the temperature
of 30 kg of liquid water from 10 0C to 20 0C ?
Q = mcΔ T
= 30 Kg x 4.19 J/kg 0C x (20-10)0C
= 1,257J
Sample Problem
A 2.0-kg aluminum pan is heated on the stove
from 20°C to 110°C. How much heat had to be
transferred to the aluminum? The specific heat
capacity of aluminum is 900 J/kg°C.
Q = cmΔT
Q = (900 J/kg°C ) (2.0 kg) (110°C - 20°C)
Q = 162,000 J
Q = 1.62 x 105 J
Evaporation
Melting
Condensation
Freezing
Latent Heat is the amount of energy needed to change
the state of a mater at constant temperature.
 Heat is a form of energy, and it is measured in
joules.
- A unit of heat common in the U.S. is the calorie,
which is defined as
the amount of heat energy needed to change the
temperature of 1 gram of water by 1 Celsius degree
1 calorie = 4.18 joules
- Conduction involves the transfer of heat through
direct contact
- Heat conductors conduct heat well, insulators do not
Heat Transfer: Convection
- Takes place in liquids and gases as molecules move
in currents
- Heat rises and cold settles to the bottom
Heat Transfer: Radiation
-Heat is transferred through space
-Energy from the sun being transferred to the Earth
Which picture shows the object that
has more kinetic energy of particles?
Figure A
Figure B
Emitters and absorbers
• The Sun gives out the heat.
• It is known as an emitter / radiator
• The Earth takes in the heat.
• It is known as an absorber.
Good and Bad
Emitters/Absorbers
• A poor emitter would be a poor absorber.
• A good emitter would also be a good absorber.
Good emitter/absorber
Poor emitter/absorber
Dull, black surface
Shiny, silver surface
Rough surface
Smooth surface