2. Temperature
• Specifically – how fast the particles are
moving, average kinetic energy
• Matter is made of atoms that are always
moving, or they have kinetic energy
• The more kinetic energy, the higher the
temperature
3. • Measuring temperature measures the average
kinetic energy of an object
• Thermal expansion – increase in the size of a
substance in response to an increase in temp
(as temp increases, particles move faster,
spreading out)
• Because of thermal expansion, all materials can
expand and shrink when temperature changes
4. Thermal Expansion Examples
Thermal expansion gets these
balloons off the ground because the
heated air expands.
The expansion joints in bridges
allow the concrete to expand and
contract without breaking.
5. • Fahrenheit
– Boiling pt 212°F
– Freezing pt 32°F
• Celsius
– Boiling pt 100°C
– Freezing pt 0°C
• Kelvin
– Boiling pt 373K
– Freezing pt 273K
• Lowest temp on Kelvin scale is 0K or
absolute zero (-459°F), the temperature
at which all molecules stop moving
6. Heat -vs-Thermal Energy
• Heat is what moves between objects with
different temperatures
• Thermal Energy is the speed of the
objects particles, remember objects with
speed have energy
• Thermal energy is transferred from areas
warmer to areas that are cooler until both
are equal
• THEY ARE NOT THE SAME THING
7. Conductors and Insulators
• Materials that transfer heat are called
thermal conductors
• Materials that do not transfer heat are
called thermal insulators
• Examples:
– Insulators: feathers, blankets, plastics
(polymers)
– Conductors: metals
• Thermal conductivity is the rate at which
a material conducts heat
8.
9. Energy Transfer
• Only 3 ways to transfer all energy
• Convection – circular motion of a gas or
liquid
• Conduction – by direct contact (touch)
• Radiation – as electromagnetic waves
10. Conduction – the transfer of energy, as
heat, through a material (touch)
11.
12. Radiation – the transfer of energy
as electromagnetic waves (sun)
13. • Radiant energy from the sun heats earth
• Examples:
– Fire
– Radiator
– Electric Oven
– Electric stove
14.
15. Convection is the transfer of thermal energy
by the circulation or movement of a liquid or
a gas (solids do not convect)
16.
17.
18. • Energy transfer can not be measured
directly, instead it must be calculated
• Heat = joules (J)
• Summary:
• Conduction – transfer by direct contact
(touch)
• Convection – movement of molecules
(rising and falling, only gas or liquid)
• Radiation – transfer by electromagnetic
waves
