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# Copy of Thermal Expansion

PHYSICS - Prezi about thermal expansion
by

## ryah coronel

on 23 September 2012

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#### Transcript of Copy of Thermal Expansion

Thermal Expansion Thermal Expansion :
*As the temperature increases, its volume increases.
* It has important role in numerous engineering applications.
*It is a consequence of the change in the average separation between the atoms in an object. < 3 types of thermal expansion of solids > 1. linear expansion
when the change is only in the length of the object the expansion is called linear expansion 2. Superficial Expansion
The change in area of a solid is called superficial expansion 3. cubical expansion
The expansion in the volume of a solid is called cubical expansion example!!
In summer, the railroad, which is a metal, gets longer. That's the reason why the railroads are seperated by little gaps to prevent the railroad to be bent Question!!
when a pingpong ball is dented, how can i expand it into normal size? Solution for you is...
1. Put the ball into the hot water.
2. In about two minutes, it will be expanded. why??
Most materials expand on heating and contract on cooling.
The heat causes the air inside the ball to expand, so the dent pops out. THANK YOU FOR
*http://www.calctool.org/CALC/eng/default/ct
*http://hyperphysics.phy-
astr.gsu.edu/hbase/thermo/thexp.html
*http://www.physicstutorials.org/home/heat-temperature-and-thermal-expansion/heat-temperature-and-expansion-cheat-sheet/86-thermal-expansion-and-contraction
*http://ffden-2.phys.uaf.edu/212_spring2011.web.dir/Corey_Aloia/bridgescold.html
*Exploring Through Science (Physics) TOPIC # 7 relating to, or caused by heat; being or involving a state of matter dependent upon temperature ther·mal \thr-ml\ ex·pan·sion \ik-span(t)-shn\ the quality or state of being expanded; something that results from an act of expanding * It is usually expressed as a fractional change in length or volume per unit temperature change 1.The change in length of an object when it undergoes a temperature change is related to
a) its original length
b) its mass
c) the magnitude of the temperature change.
d) both a & c
e) a, b, & c Linear Expansion Formula Body The area thermal expansion coefficient relates the change in a material's area dimensions to a change in temperature Area Expansion Formula If the objects expand in volume with the gained heat, we call this volume expansion and find it using this formula: Volume Expansion Formula Water shows unusual expansion. If we take a cube of ice at -5°C and heat it, it expands till ice starts melting. During melting its temperature remains 0°C but its volume decreases. If heat is continuously supplied to water at 0°C, it further contracts up to 4°C and then it starts expanding. Thus water has its minimum volume and maximum density at 4°C. Anomalous Behavior of Water *The anomalous expansion of water helps preserve aquatic life during very cold weather. *When temperature falls, the top layer of water in a pond contracts, becomes denser and sinks to the bottom.
*A circulation is thus set up until the entire water in the pond reaches its maximum density at 4°C. If the temperature falls further, the top layer expands and remains on the top till it freezes.
* The upper layer are frozen the water near the bottom is at 4°C and the fishes etc. can survive in it easily. * ANSWERS* 1. D
2. D
3. B
4. B
5. D
6. A
7. C
8. A
9. C
10. E CORONEL, RYAH LIZZA M.
MARISTELA, ZYRNA Y.
BS BIOLOGY- 2B *REPORTERS* *It may be helpful to think of thermal expansion
as an effective magnification
or as a photographic enlargement of an object. * THERMAL EXPANSION JOINTS *Are used to separate sections of roadways on bridges. *This joints must also be included in buildings, concrete highways, railroad tracks, brick walls, and bridges. *These joints compensate for dimensional
changes that occur as the temperature changes * Without these joints, the surfaces would buckle due to thermal expansion on very hot days or crack due to contraction on very cold days. *The bridges in the images above
reportedly collapsed due to thermal expansion.One girder buckled, creating a chain reaction and causing the rest to buckle. * This is what an actual thermal expansion joints looks like. * LINEAR EXPANSION FORMULA* It is a characteristic property of a material of solid and is defined as:
*" increase in length per unit original length per Kelvin rise in temperature is known as coefficient of linear expansion". * It is denoted by "alpha". *Let a1 = area of a surface

*t1 = its initial temperature

*a2 = area of the surface after
heating

*t2 = final temperature (Topic #7- Thermal Expansion)
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