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Differentiate between

conduction, convection, and

radiation.

Explain molecular motion as it relates to thermal energy changes in terms of conduction, convection, and radiation.

Explain common examples, such as ice in a soda, to show the direction of energy flow.

GOALS

Determine the heat

capacity of a

substance using mass,

specific heat, and

temperature.Use a calorimeter

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Temperature and Temperature and HeatHeat

•TemperatureTemperature is the measurement of the avg. KE of the molecules in a material.

•HeatHeat is the transfer of KE from one material to another.

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CO N DUCT I O N CO N VECT I O N RA DI A T I O N

T H ERM AL EN ERGY T RA N S FER

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ConductionConduction•The transfer of thermal energy in solids.

•Materials must be in direct contact with each other!

•Ex: Heating of the bottom of a pot on stove.

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ConvectionConvection•Transfer of thermal Transfer of thermal energy in liquids and energy in liquids and gases.gases.

•The matter actuallyThe matter actually movesmoves from one place from one place to another.to another.

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RadiationRadiation

•Transfer of thermal Transfer of thermal energy by energy by electromagnetic waveselectromagnetic waves (we’ll discuses these more later)(we’ll discuses these more later)

•Transferring energy Transferring energy through space...through space...NO NO MATTER IS REQUIRED!MATTER IS REQUIRED!

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Specific HeatSpecific Heat•Adding Energy to a material

Causes the•Temperature to go up.•Taking energy away from a

substance causes the temp. to

•Go down!

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•Have you ever noticed that on a hot summer day the pool is cooler than the hot cement?

•OR maybe that the ocean is cooler than the hot sand?

•Why? The sun has been beating down on both of them for the same amount of time...........

•It takes more thermal energy to raise the temperature of water that it does the cement!

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Water Water absorbsabsorbs a lot a lot of heat energy of heat energy before its before its temperaturetemperature changes while changes while sandsand needs little heat needs little heat energy before its energy before its temperature temperature increases.increases.

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Specific HeatSpecific Heat•The amount of energy required to raise the temperature of a material (substance).

•It takes different amts of energy to make the same temp change in different substances.

•We call the amt required: Specific Heat!

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Example:Example:Specific Heat of Specific Heat of

WaterWater•Cp = 4,184 Joules of energy to raise the temperature of 1kg 1°C.

• video clipWhy Cp?

Cp Stands for “Heat Capacity”

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Specific Heat of Specific Heat of waterwater

•The Cp is high because H2O mols. form strong bonds w/each other.

•It takes a lot of energy to break the bonds so that the the molecules can then start to move around faster (HEAT UP).

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Calculating Specific Calculating Specific HeatHeat

The Greek letter Δ means “change The Greek letter Δ means “change in”in”

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EXAMPLE : p162•Mass = 45kg•Q = 203,000J•Δt = 40°-28°•Δt = 12° •Cp = ?•Q =m x Cp x Δt•Q/(m x Δt) = Cp•Cp = 376 J/(kg °C)

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A by traveling through space as waves

B by the movement of fluids

C by the expansion of gasesD by contact between

particles

Conduction can BEST be described as the transfer of

energy

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