the theory of heat reporting

8/11/2019 The Theory of Heat reporting

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R E P O R T E D B Y :

C I A R A M A R Y B . C A N S A N C I O

The theory of heat


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What is heat?It is a form of energy

that flows from onesubstance to anotherthat is at a lowertemperature.

Its standard unit isJOULE named after

James Prescott Joule.

It is also called thermalenergy and commonlyused symbol foramount of heat is Q.


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Temperature

It is the property of asubstance that gives thesensation of hotness orcoldness.


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Thermometer

Device used to measuretemperature.


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Optical pyrometer

Device used to measurevery high temperature

without touching theobject. This temperaturemeasuring deviceoperates on the principlethat the color of the lightgiven off by glowing

objects depends on itstemperature.


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Temperature Scales:

1.) Celsius scale (centigrade Scale)

2.) Fahrenheit Scale

3.) Kelvin Scale


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Temperature

Scales:

1.) Celsius scale(centigrade Scale)

was a device by AndersCelsius based on theproperty of water ofwater that 0 and boilingpoint is 100


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Temperature

Scales:

2.) Fahrenheit Scale

developed by DanielGabriel Fahrenheit. Inthis scale, 32 is thefreezing point of waterand 212 is theequivalent for boilingpoint.


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Temperature

Scales:3.) Kelvin Scale

-named after Lord Kelvin(William Thomson).Used when gasses areinvolved. Its zero point (0

k) corresponds to -273 isreferred to as absolutezero or temperature at

which matter is said tohave lost all its thermalenergy.

-It is called the standardscale or the absolute

scale.

-Kelvin Scale is thestandard SI unit oftemperature.


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Internal Energy

Total kinetic and potential energy of the particles of asubstance.

When heat flows into an object, its internal energy

increases. When heat flows out of the object, its internal energy

decreases.


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ThermalEquilibrium

-A system is in thermalequilibrium when all ofits parts have the sametemperature.

Zeroth law ofthermodynamics

-states that if twoobjects are inequilibrium with a third

object, then these twoobjects are in thermalequilibrium with eachother.


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Thermal expansion

The changes in the dimensions of solid, liquid or gasoccurring due to the charge in temperature.

When a material is heated, its particles move faster, allowing

each other to move farther from its equilibrium position. Thismeans that each particle needs more room to move about in.The overall effect is that material expands.

Thermal expansion may occur in three 3 dimensions:

1.) Linear expansion2.) Surface expansion

3.) Volume/Bulk expansion


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Thermal Expansion

1.) Linear expansion

occurs when the material is long but narrow.

The dimension that changes is the length.


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Thermal Expansion

2.) Surface expansion

expansion is in terms of its surface area.


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Thermal Expansion

3.) 3.) Volume/Bulk expansion

occurs when all 3 dimensions undergoconsiderable expansions.


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Heat exchange

Why do warm and coldbodies placed side byside attain the sametemperature

eventually?Heat flows from the warm

body to the cold bodybecause of the unequaltemperatures, which inthe process reduces thewarm bodystemperature. The heat

that flows into the coldbody increases thebodys temperature.


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Heat Capacity

The amount of heat that a given mass of substanceabsorbs or releases to undergo a temperature changeof 1.

The standard unit for heat capacity is joule perKelvin (J/K).

Specific heat capacity

Refers to the amount of heat that a unit mass of a

substance absorbs or losses to change itstemperature by 1.


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Heat Exchange

Law of conservation of energy

Implies that if the energy of an object goes up (or it istemperature goes up), that energy is not newly created energy.The energy comes from a source, which is the warm body.

Law of heat exchange The amount of energy that the warm body lost is the same as

the amount of that cold body gained. This can also be stated asfollows:

Heat gained (by cold body) + heat lost (by warm body) = 0

the theory of heat reporting

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