Thermal EnergyThermal Energy

TemperatureTemperatureMeasures the “hotness” (higher

temperatures) or “coldness” (lower temperatures)

Gives very little information on the energy that the material contains.

Temperature HeatTemperature Heat

Some equate temperature to heat

Temperature and Heat are not the same

TemperatureTemperatureAll matter is made up of tiny

particlesThese tiny particles are

constantly moving

All moving things have kinetic energy

The faster the particles move the more KE

The temperature is a measure of the average Kinetic Energy

Thermal EnergyThermal EnergyPlace a ice-cold spoon on ice cream.

What happens?Place a hot spoon on ice cream. What

happens?

Place two hot spoons on ice cream. How is it different?

Pour hot water on the ice cream. How is this different from the spoon?

Thermal EnergyThermal EnergyThermal energy is the total

amount of kinetic and potential energy of a material

Kinetic energy determined by the speed of the moving particles

Potential energy determined by the distance between the particles

Thermal Energy & TemperatureThermal Energy & Temperature

They are relatedAs temperature increase so does the

kinetic energy and the potential energy of the particles

Thermal EnergyThermal Energy

Depends upon temperatureMass of materialType of material

HeatHeat

The transfer of thermal energy

HeatHeatHeat is the energy that flows

from an object of higher temperature to an object with lower temperature

Heat is measured in units of Joules

Does an ice cube in warm water cause the water to cool down

Or does the warm water cause the ice cube to melt?

So…

Specific HeatSpecific Heat

Why is the air around the swimming pool warmer than the water even if they have both been exposed to the sun the same amount of time?

Different materials need different amounts of heat to change the temperature the same amount.

Copper pot –vs- water

Specific Heat is the amount of heat necessary to raise the temperature of one kilogram of a material one degree Celsius

Units (J/kg.Co)Specific heat of water very

highAdvantages?Disadvantages?

Measuring Specific HeatMeasuring Specific Heat

Cannot measure the amount of heat energy transferred

Can only measure the resultant change in thermal energy

Q = mcTm-mass in grams or kilogramsQ- thermal energy in Joulesc-specific heat in J/kg.Co or

J/g.Co

T-change in temperature in Co

Change in LengthChange in LengthWhen temperature is

increased objects expandSidewalks, siding on

houses, railroad tracks, bridges, etc…

l=lTl-change in lengthl-original lengthcoefficient of linear

expansionT-change in temperature

Change in VolumeChange in VolumeLiquids expand 100 times

more than solidsV=VT

V-change in volumeV-original volumecoefficient of volume

expansionT-change in temperature