Heat is a form of:

Everything in the universe has heat energy! Your BODY, your CAR…even ICE!

Temperature: Temperature is ONLY a

measurement. Temperature measures

the average kinetic energy of the molecules of an object or substance.

SUMMARY:HEAT IS ENERGYTEMPERATURE IS A MEASUREMENT

Temperature is measured with thermometers.

There are several types of thermometers.

THERMOMETER TYPES:1) Liquid Thermometer2) Bimetallic strip3) Digital

Liquid ThermometerCan only measure temperatures in a certain range.Uses the expansion of liquid alcohol or mercury (Hg) to indicate changes in temperature.

Bimetallic StripA coil is made using two different metal strips pressed togetherBoth strips expand and contract at different rates as the temperature changesAs the temperature changes, the coil winds and unwinds

DIGITAL THERMOMETERSMeasures temperature by noting the change in current

Changes in temperature also cause electric current to change in a circuit

3 Main Temperature Scales

1)Celsius2)Fahrenheit3)Kelvin

What you need to know about the Fahrenheit Temperature Scale

1)1) Fresh water Fresh water freezesfreezes at at 3232 degrees degrees FahrenheitFahrenheit

2)2) Fresh water Fresh water boilsboils at at 212212 degrees degrees FahrenheitFahrenheit

What you need to know about the Celsius Temperature Scale

1) Fresh water freezes at 0 degrees Celsius

2) Fresh water boils at 100 degrees Celsius

3) It is the commonly used scale except for in the United States

What you need to know about the Kelvin Temperature Scale

1) There are NO NEGATIVE NUMBERS

2) Based on absolute zero (all molecule movement has stopped).

3) The size of a Kelvin degree is equal in magnitude (size) to a Celsius

degree.

Heat moves from objects with higher energy to objects with lower energy

DEMO-Is it hot or is it cold?

HEAT CAN MOVE IN 3 WAYS

1) CONDUCTION2) CONVECTION3) RADIATION

For heat to be transferred by conduction:

objects must be in direct contact with each other—

THEY MUST BE TOUCHING!!!

Convection: Transfer of energy by

the movement of fluids with different temperatures For it to be fluid, it

can be a liquid or a gas!

Radiation: Transfer of energy by

electromagnetic waves NO DIRECT CONTACT!!! Does not require a

medium to travel! It is the only way solar

heat energy can travel to Earth!

Some objects act as conductors and some act as insulators.

A conductor is a material that transfers heat quickly

An insulator is a material that slows the transfer of heat

Specific HeatSpecific Heat Describes how much energy is required to Describes how much energy is required to

raise an object’s temperature.raise an object’s temperature. The specific heat value is how much The specific heat value is how much

energy is required to raise 1 kg. of a energy is required to raise 1 kg. of a substance by 1 degree Kelvinsubstance by 1 degree Kelvin

Denoted by “c” in calculationsDenoted by “c” in calculations

Specific Heat EquationSpecific Heat EquationEnergy = (specific heat) x (mass) x Energy = (specific heat) x (mass) x

(temperature change)(temperature change)OROR

energy = cm tenergy = cm t

When the temperature of a substance When the temperature of a substance is increased, its molecules move is increased, its molecules move faster and usually move farther faster and usually move farther apart. This is apart. This is thermal expansionthermal expansion. It . It occurs in all forms of matter (there occurs in all forms of matter (there are a few exceptions). are a few exceptions).

Water is an exception – it expands Water is an exception – it expands when it is cooling from 4 degrees C when it is cooling from 4 degrees C to 0 degrees C.to 0 degrees C.

To raise indoor air temperature To raise indoor air temperature on a cold day, energy must on a cold day, energy must be transferred into a room’s be transferred into a room’s air by a heating system.air by a heating system.

Heating system – Any device Heating system – Any device or process that transfers or process that transfers energy to a substance to energy to a substance to raise the temperature of the raise the temperature of the substance.substance.

Types of Heating Types of Heating Systems:Systems: Forced Air Forced Air

SystemsSystems Radiator SystemsRadiator Systems Electric Heating Electric Heating

SystemsSystems

Heating and Work increase thermal energyHeating and Work increase thermal energy You can warm your hands by either You can warm your hands by either

placing them near a heat source or placing them near a heat source or rubbing them togetherrubbing them together

In this example, your hands would be In this example, your hands would be considered to be a system.considered to be a system. A system can be a group of objects A system can be a group of objects

you can draw a boundary around to you can draw a boundary around to consider certain values about a consider certain values about a scenario.scenario.

THERE ARE 2 TYPES OF SYSTEMS:THERE ARE 2 TYPES OF SYSTEMS: OPENOPEN-Thermal energy can flow across -Thermal energy can flow across

your “boundary” or if work is done across your “boundary” or if work is done across the boundarythe boundary

CLOSED – CLOSED – Thermal energy is contained Thermal energy is contained within the “boundary” and no outside within the “boundary” and no outside work is done.work is done.

First Law of First Law of ThermodynamicsThermodynamics

The increase in the The increase in the thermal energy of a thermal energy of a system equals the work system equals the work done on the system done on the system plus the thermal energy plus the thermal energy transferred to the transferred to the systemsystem

Second Law of Second Law of ThermodynamicsThermodynamics

Energy moves from Energy moves from warmer objects (higher warmer objects (higher energy) to cooler energy) to cooler objects (lower energy)objects (lower energy)

Cooling System – A device that transfers Cooling System – A device that transfers energy as heat out of an object to lower energy as heat out of an object to lower its temperature.its temperature.

Cooling Systems use evaporation to transfer Cooling Systems use evaporation to transfer energy from their surroundings using a energy from their surroundings using a refrigerantrefrigerant

Refrigerant – A substance used in cooling Refrigerant – A substance used in cooling systems that transfers large amounts of systems that transfers large amounts of energy as it changes stateenergy as it changes state