Transcript Chapter 11.2 “What is Heat” Notes

Chapter 11.2
“What is Heat” Notes
Assignment #
# 4th Period
Heat
• What is heat?
• Has to do with hot
AND cold
• The thermal energy
transferred between
objects that are at
different temperatures
Thermal Energy
• Thermal Energy
• The total kinetic
energy of the particles
that make up a
substance
• Depends on:
– Temperature
– Amount of substance
Thermal Energy and Temperature
• Why does thermal
energy depend on
temperature?
• More thermal energy
in a substance at a
high temperature than
at a low temperature
Thermal Energy and Amount of
Substance
• Why does thermal
• The more particles in
energy depend on the
a substance at a
amount of substance?
given temperature,
the more thermal
energy
Heat Transfer Between Objects
• What happens when
objects at different
temperatures come
into contact?
• Energy is transferred
• Thermal energy
transferred from the
warmer object to the
cooler object until
both have the same
temperature
Efficiency of Heat Transfers
• Are thermal energy
transfers efficient?
• They are not 100%
efficient
– Some energy is lost as
heat to the
surroundings
Thermal Conduction
• Thermal Conduction
• The transfer of
thermal energy from
one substance to
another through direct
contact
– From substance to
another
• Hot soup to a metal
spoon
– Within one substance
• Bottom of spoon in
soup up to your hand
Conduction
How Does Thermal Energy Occur?
• When objects touch, their particles collide
– Thermal energy transfers from substances at
a higher temperature to substances at a lower
temperature
– The particles with a higher kinetic energy
transfer energy to particles with a lower
kinetic energy
– Some particles slow down, while others speed
up
– Eventually, all particles have the same
average kinetic energy and the same
temperature
Thermal Conductors & Insulators
Thermal Conductors
• Substance that
conducts thermal
energy very well
(material through
energy can be
transferred as heat)
–
–
–
–
Curling iron
Cookie sheet
Copper pipe
Metal spoon
Thermal Insulators
• Substance that does
not conduct thermal
energy well (material
that reduces or
prevents the transfer
of heat)
–
–
–
–
Oven mitt
Plastic spatula
Wooden spoon
Ceramic bowl
Convection
• Convection
• The transfer of
thermal energy by the
movement or
circulation of a liquid
or a gas
• Continuous, circular
motion
– Dense, cold air rises
while less dense, hot
air rises
Convection Currents
• Convection Current
– A circular motion of gases or liquids due to
density differences that result from
temperature differences
– Convection currents caused by the uneven
heating of the Earth’s surface are responsible
for Earth’s winds, weather patterns, and
ocean currents
• Without these currents, Earth’s climate would be
very different!
Radiation
• Radiation
• The transfer of energy
by electromagnetic
waves
Heating of the Earth by Radiation
How many methods of heat
transfer are occurring?