heat miller. introduction: temperature = a measure of the average kinetic energy in a substance....
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HEATHEATMiller
Introduction:Introduction:Temperature = a measure of
the AVERAGE kinetic energy in a substance.
Heat energy is measure in Joules
ExpansionExpansionDef: When objects are heated up
and their temperature increases, they will normally expand .◦The molecules move farther apart.
ContractionContractionDef: When objects cool down
they will normally contract. ◦The molecules come closer together.
Absolute Zero:Absolute Zero:0K or -273 ˚C
◦All molecular motion stops◦Is only a theory◦The basis for the Kelvin scale
Temperature Scales:Temperature Scales:Kelvin
◦0 K is the lowest temp possible This is absolute zero
Fahrenheit ◦Freezing point of water 32◦ F, and the
boiling point is 212◦F.Celsius
◦Freezing point of water is 0◦C, and the boiling point is 100◦C.
◦Scientists use the Celsius scale
Converting Fahrenheit to Converting Fahrenheit to CelsiusCelsiusTo convert temp from ◦F to ◦C:◦C= (5/9) (◦F-32)
To convert temp from ◦C to ◦F: ◦F= (9/5) (◦C ) + 32
To convert temp from ◦C to K:K = ◦C + 273
Example:Example:To convert 68 ◦F to ◦C, first subtract
32 , multiply by 5 and then divide by 9. The result is 20 ◦C.
*Remember: ◦C= (5/9) (◦F-32)
◦C= (5/9) (68◦F-32)
◦C= (5/9) (36)◦C=180/9◦C= 20
Heat:Heat:Def: The transfer of energy
between objects that are at different temperatures;
Energy is always transferred from higher-temperature to lower-temperature objects, until thermal equilibrium is reached.
3 Types of Heat Transfer:3 Types of Heat Transfer:
Conduction
Convection
Radiation
Heat Transfer #1:Heat Transfer #1:
Conduction = transfer of heat by direct contact (molecule to molecule)◦Ex- metal spoon in a hot bowl of soup
◦Conductors- conduct thermal energy very well Ex- Iron, steel, gold
◦Insulators- Do NOT conduct thermal energy well Ex – rubber, plastic, wood
Examples:Examples:Conductor(metal)
Insulator (rubber)
Heat Transfer #2:Heat Transfer #2:Convection = Transfer of
energy by convection currents in liquids
and gasesWarmer fluids are less dense
than colder fluids, thus warm fluids rise and cold fluids fall.◦ fluid = anything that flows (liquids & gases)◦ not possible in solids◦ hot air balloons, “convection” ovens
Example:Example:The water at the bottom of a pot on
a stove burner gets hot because of contact with the pot itself (conduction).
As a result, the hot water becomes less dense because its higher-energy particles have spread apart.
As the warm molecules rise to the top of the pot the cooler molecules sink back down into the pot.
This circular motion creates a convection current.
Heat Transfer #3:Heat Transfer #3:
Example:Example:The coils of an open heater warm
a room by radiating visible light and infrared waves.
Thermal Energy:Thermal Energy:Def: The total energy is equal to
the particles that make up a substance.
An object at a high temperature has more thermal energy than the same object at a lower temperature.
The more moving particles that you have, the greater the thermal energy!!
Example:Example:When you hold an ice cube in
your hand, thermal energy is transferred from your hand to the ice cube.
The ice cube’s thermal energy will increase and your hand’s thermal energy will decrease!!◦THIS MAKES YOUR HANDS FEEL
COLD!!
Thermal Conductivity:Thermal Conductivity:Def:
The amount of energy at which a substance conducts thermal energy.
Specific Heat Capacity:Specific Heat Capacity:Def: The amount of energy
needed to change the temperature of a 1kg object by 1˚C.
The law of conservation of The law of conservation of energy:energy:States that; energy cannot be
created or destroyed.
Review:Review:What are the 3 types of
temperature scales?
Kelvin, Fahrenheit, and Celsius
Review:Review:List the three types of thermal
energy transfer and give an example of each.
Conduction- molecules have to be touching!!
Convection- thermal heat currents
Radiation- travels is waves
Review:Review:What is the difference between
heat and temperature?
Temperature = a measure of the AVERAGE kinetic energy in a substance.
Heat=The transfer of energy between objects that are at different temperatures.
Review:Review:What is absolute zero?
0K or -273 ˚C◦All molecular motion stops◦Is only a theory◦The basis for the Kelvin scale
Review:Review:If it is 62 ◦F outside today, what would
the temperature be in ◦C?◦16.66 ◦C
What would it be in K?◦289.66 K