Download Section 1: Temperature and Heat Temperature A measure of the

Section 1: Temperature and Heat
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Temperature
A measure of the average kinetic energy of the particles in the object.
As temperature increases, the average speed of the particles increases
• SI unit:
• Kelvin (K)
• In science:
• Celsius
• To us:
• Fahrenheit
• Body temperature:
• 37oC, 98.6oF
Absolute zero
 Temperature at which molecular energy is at a minimum
 Particles NEVER completely stop moving
 Basis for:
 Kelvin Scale
 1 K= 1oC on Celsius scale
 Only difference is how zero is determined
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Heat
Transfer of energy between objects that are different temps.
Always flows from higher temp lower temp
SI unit: joules (J)
Factors Affecting Heat
How much heat an object absorbs or loses
 Mass of object
 Temperature change of object
 final temp- initial temp
 If there is not change, no heat flow
 Composition of object
Section 2: Transferring thermal energy
Convection
 Transfer energy in a fluid by the movement of warmer and cooler fluid from place to place.
 Fluids
 Liquids and gases
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Radiation
Energy transfer by electromagnetic waves
Different:
• Doesn’t involved the movement of matter across space
Conduction
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Transfer of energy by collisions between particles in matter that are in constant motion
Conductors
• Material through which energy can be transferred as heat
• Example: metals
Insulators
 A material in which heat flows slowly
 Examples:
 wood, fiberglass, air
 Determiners:
 How much energy is required to change the temp of the substance
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Specific heat
Heat required to raise the temperature of 1kg of material by 1K
SI unit: J/(kg•K)
Water:
• 4,186 J/(kg•K)
Specific heat cont’d
 Energy=specific heat x mass x temp. change
 Q=mc∆T
 Adding energy:
 Raises its temp or state of matter but not both at the same time
Section 3: Using heat
Thermodynamics
 First law of thermodynamics
 Total energy used in a process is conserved whether the energy transferred as a result
of work, heat, or both
 Second law of thermodynamics
 Heat transferred as heat always moves from a higher temp. to a lower temp.
Mechanical Processes
 Processes in which energy is transferred by work
 Example:
 Rubbing two sticks together to create fire
Heat engines
 Chemical energy is converted to mechanical energy through process of combustion
 Two types
 Internal combustion
 4 strokes: Intake, compression, power, exhaust
 External combustion