Intro to Thermal EnergyIntro to Thermal Energy

November 7, 2013November 7, 2013

ObjectivesObjectives

1.1. Explain the motion of molecules in Explain the motion of molecules in the different states of matterthe different states of matter

2.2. Understand the definition of Understand the definition of thermal energy and what happens thermal energy and what happens in thermal equilibriumin thermal equilibrium

Movement of atomsMovement of atoms• All matter is constantly movingAll matter is constantly moving

• Moving particles determines whether Moving particles determines whether an object is solid, liquid, or gasan object is solid, liquid, or gas

Kinetic EnergyKinetic Energy

• The warmer an object is the more The warmer an object is the more kinetic energy it haskinetic energy it has

Thermal EnergyThermal Energy

• The total energy of all it’s atoms and The total energy of all it’s atoms and moleculesmolecules

Flow of Thermal EnergyFlow of Thermal Energy

•From a warmer substance to a From a warmer substance to a colder onecolder one

•HEAT – thermal energy in motionHEAT – thermal energy in motion

Hot or ColdHot or Cold

• TemperatureTemperature

• Thermometer measures temperature Thermometer measures temperature by expansion or contraction of a by expansion or contraction of a liquidliquid

Eureka 20Eureka 20

TemperatureTemperature

• Related to the Related to the randomrandom motion of atoms and motion of atoms and moleculesmolecules

•averageaverage kinetic energy of kinetic energy of moleculesmolecules

• Thermometers read their own Thermometers read their own temperaturetemperature

• Energy flows between the Energy flows between the thermometer and the object until thermometer and the object until they reach an equal temperaturethey reach an equal temperature

• This equilibrium is called a Thermal This equilibrium is called a Thermal equilibriumequilibrium

Upper Limit of Temperature

Solid Liquid Gas

What happens after the Gas state?

Plasma – Cloud of electrically charged particles- stars, millions of degrees C

What’s cold?What’s cold?

•The absence of thermal energyThe absence of thermal energy

•An object is cold because of the An object is cold because of the loss in thermal energyloss in thermal energy

•Eureka 21Eureka 21

Heat – change in EtHeat – change in Et

•Measured in JoulesMeasured in Joules

•4.2 Joules = heat to change 1 4.2 Joules = heat to change 1 gram of water 1 Celsius degreegram of water 1 Celsius degree

ccaloriealorie•Unit of heat used in the United StatesUnit of heat used in the United States

•Amount of heat needed to change 1 gram of Amount of heat needed to change 1 gram of water 1 Celsius degreewater 1 Celsius degree

•c = Mass (Change in temp)(specific heat)c = Mass (Change in temp)(specific heat)

•1 1 ccalorie = 4.2 joulesalorie = 4.2 joules

•Water’s specific heat = 1Water’s specific heat = 1

•Energy ratings of food and fuels Energy ratings of food and fuels are measured by the energy are measured by the energy released when they are burnedreleased when they are burned

•KiloKilocalories = calories = CCalories we know alories we know on food packages (capitol C)on food packages (capitol C)

•To the Weight Watcher, the To the Weight Watcher, the peanut contains 10 peanut contains 10 CCaloriesalories

•To the physicist, it releases To the physicist, it releases 10,000 10,000 ccalories of energy when alories of energy when burned or digestedburned or digested