Presentation on theme: "Chapter 9 Thermal Energy"— Presentation transcript:
1Chapter 9 Thermal Energy HeatChapter 9 Thermal Energy
2Kinetic and Potential Energy Kinetic energy- energy of motionpotential energy – Is the certain amount of energy that Molecules have that is ABLE to be changed to kinetic energy
3*Thermal EnergyBoth the potential energy + the kinetic energy of all the molecules in an object is: Thermal Energy.
4What is Temperature?Temperature- is a measure of the average movement of molecules(kinetic energy)(You know it as “How hot or cold something is”)Higher temperatures mean faster moving molecules in a substance
5Temperature Scales Three Common Temperature Scales (units) Fahrenheit is used mainly in the United StatesCelsius is based on water’s freezing and boiling pointsKelvin, uses zero as absolute zero, the lowest temperature an object can have.
6Converting Temperatures Convert Fahrenheit to CelsiusC = 5/9 ( Temperature in Fahrenheit - 32)Convert Celsius to FahrenheitF = 9/5 ( Temperature in Celsius) + 32Convert Celsius to KelvinK= Temperature in Celsius + 273PEMDAS DOES COUNT!!!!!
7Thermal ExpansionWhen most substances are heated they expand, The amount they expand depends on the material and temperatureThat means the molecules speed up and tend to move farther apart*This means things that are cooled slow down their particles, which get closer….causing it to contract or shrink
9What is Heat?Heat- A form of energy (thermal) made by the motion of molecules.The more movement of molecules the more heat energyHeat energy has the ability to do work
10Finishing Heat’s Definition Heat: is thermal energy that is TRANSFERRED from one object to another when the objects are at different temperatures.So there must be a difference in temperatures for heat to transfer!
11DO NOT WRITE Heat & States of Matter Solids have vibrating particles, not moving freely,add heat and the solids melt, to liquidsLiquids have less restricted moving particlesAdd heat and the liquid evaporatesTo the most freely moving particles of a gasThe opposite is true when you remove heat, from gas to liquid to solid*Thermometers
12Transferring HeatHeat ONLY flows from warmer objects to cooler objectsHeat NEVER flows from colder objects to warmer objectsHeat transfer occurs in three waysConductionRadiationConvection
13Conduction Conduction- This is the transfer of heat by direct contact… …This is done by the contact between particles of high kinetic (moving) energy to particles of low kinetic energyTransfer will continue until all particles have the same kinetic energy and are the same temperatureOccurs more easily in solids and liquidsExample:Attempting to eat a hot pocket and you burn your mouth
14Radiation Radiation- Transfer of energy by electromagnetic waves. This can occur in space or through matter since it does not require particles to transfer the energyThis is how the sun’s energy reaches Earth
15ConvectionConvection- Heat transfer that occurs in moving fluids (liquids and gases), the movement of molecules from one part of a material to another.Hot liquids & gases rise while cold ones fall. This creates currents that carry the heat energyWind is caused by convection
16Good and Poor Conductors Conductors: material that easily transfers heatPoor Heat ConductorsWoodPlasticGlassGasesGood Heat Conductors-Most metals
17InsulationInsulation: is used to reduce the amount of heat loss by conductionPoor Conductors are good insulatorsMaterials that trap air are good insulators
18DO NOT WRITE Heat Transfer Used in heating systems of homes and other buildingsUsed in Cooling Systems tooHeatingFireplace-RadiationSteam Heating-Uses all 3Hot Water Heating-Uses all 3ElectricalSolarCooling*Uses evaporation to absorb heatAir ConditionersRefrigerators
19Heating an ObjectSpecific Heat: This is the amount of heat needed to raise the temperature of 1 kg of a substance by 1 Degree Celsius (depends on the material)Thermal Equilibrium: This is when there is no heat movement between two things, because both objects have reached an equal amount of thermal energy.
20Three Laws of Thermodynamics First Law of Thermodynamics: Aka> The Law of Conservation of Energy. The amount of energy in the universe remains constant.Second Law of Thermodynamics: Any process will tend to increase the amount of entropy (chaos) in the universe!!!!Third Law of Thermodynamics: As the temperature approaches absolute zero, the entropy of a system approaches its minimum.