Heat
Today we’ll talk about:
Heat
Ultraviolet Radiation
Temperature
Thermal Energy

Review
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Energy
Potential energy
Kinetic energy
Law of Conservation of
Energy
Electromagnetic
Spectrum
Ultraviolet Light

Today we will learn:
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The dangers of Ultraviolet radiation and where it is.
What heat is and how it transfers.
About Thermal Energy and how to tell which substance has more energy.
What temperature is and how a Thermometer works
 The different Temperature measuring systems.

UV: Ultraviolet Radiation
UV radiation is part of the Electromagnetic Spectrum.
Radiation is also a part of heat transference.

UV Radiation
Where do you find UV
Radiation?

UV Radiation
Where do you find UV
Radiation?
Is it harmful?

UV Radiation
This is a picture of an average person. Her face looks healthy.

UV Radiation
This is the same person through a UV filter.
It shows the hidden UV skin damage.

UV Radiation
This person has greater UV skin damage.

The UV Index for
,
for
Tuesday, April 21, 2009:
8-10
VERY
HIGH
“Protection against sun damage is needed. If you need to be outside during midday hours between 10 a.m. and 4 p.m., take steps to reduce sun exposure. A shirt, hat and sunscreen are a must, and be sure you seek shade. Beachgoers should know that white sand and other bright surfaces reflect UV and can double UV exposure.”

UV Forecast for Thursday, April 23

The Law of Conservation of Energy
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States…

The Law of Conservation of Energy
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States…Energy is not really lost or destroyed, but it can change.
UV Radiation & other forms of Energy from the
Electromagnetic Spectrum often change into Heat
Energy.
Radiation is also a form of Heat transfer. Think how you feel when you are exposed to the sun.
 But what is Heat?

What is Heat?
 Heat is Thermal Energy that moves from a warm object to a cool one.
 Have you every held a piece of ice? What happened when you did?

What is Heat?
It melted…what happened to the Heat
(Thermal Energy) as it melted?

What is Heat?
The Heat from your hand transferred to the ice.
Notice that your hand felt cold.

What is Heat?
That’s because some of the Heat left your hand!

What is Heat?
That’s how Heat is transferred. It goes from a hot object to a cooler one until they are both the same temperature.
There’s a demonstration that shows this.

Supplies:
2 cups
1 conductor
1 Kg Water
1 digital Thermometer

Both cups of water will reach the same temperature.

Thermal Energy
We talked about Thermal Energy, but what is it?

Thermal Energy
Thermal Energy is the total energy of all the particles in object.

Thermal Energy
Thermal Energy depends on the:
 Number of particles in the object
 The arrangement of particles
 Temperature

Thermal Energy
Example #1
The more particles an object has, the higher the Thermal Energy.
In other words, the more of an object that you have, the more energy it has.

Thermal Energy
Example #2
The arrangement of the particles affects the
Thermal Energy.
In other words, the more spread out the particles are (like a gas), the more
Thermal Energy it has.

Thermal Energy
Example #3
The higher the Temperature , the higher the thermal energy.
If an object is 80 o F, then it has higher
Thermal Energy than the same object at 50 o F...

Thermal Energy
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Thermal Energy
Now which has more Thermal Energy?
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0.5 L bottle of Dasani water
2 L bottle of Dasani water

Thermal Energy
Ok, here’s a tricky one, which has higher Thermal Energy?
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2 L bottle of Dasani
2 L bottle of water vapor

Temperature
We know the thermometer measures
Temperature.
But what is it?

Temperature
Temperature is the measurement of the average
Kinetic Energy of the particles of an object…

Temperature
In other words:
Temperature measures the motion of the particles in a substance.

Temperature
How does the
Thermometer work?

Remember that Heat expands particles.
The hotter the substance, the more the liquid expands (& the higher it rises)

Temperature
Let’s try it out!
First, we check our thermometer at room temperature.

Temperature
When heated, the liquid expands.
Let’s add more
Thermal Energy.

Temperature
More…

Temperature
What happens when it reaches the top and we add Thermal
Energy?

Temperature

Temperature Systems
These are some systems for measuring temperature:
 Fahrenheit
 Celsius
 Kelvin

Temperature Systems
Fahrenheit is the most common measuring system in the U. S.
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Boiling Point: 212º F
Room Temperature: 72º F
Freezing Point: 32º F
Absolute Zero : 460º F

Temperature Systems
Celsius is the metric version of Fahrenheit. It is the standard system used worldwide.
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Boiling Point: 100º C
Room Temperature: 23º C
Freezing Point: 0º C
Absolute Zero: 273º C

Temperature Systems
Kelvin is often used in science. It is useful for describing temperature extremes.
 Boiling Point: 273 K
 Freezing Point: 373 K
 Room Temperature: 296 K
 Absolute Zero: 0 K

Temperature Conversion Chart
Water boils
Room Temperature
Water Freezes
Absolute Zero o F o C K
212
72
32 0
100
23
-460 -273 0
373
296
273

Vocabulary
 Temperature
 Thermometer
 Absolute Zero
 Thermal energy
 Heat

Vocabulary
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Temperature: The measure of the average kinetic energy of individual particles.
Thermometer: An instrument that measures temperature
Fahrenheit Kelvin Celsius.
Absolute Zero: When no more energy can be removed from a substance.
Thermal energy: The total energy of all the particles in object
(aka: internal energy) Thermal energy depends on: the number of particles, the temperature, and the arrangement of particles.
Heat: Is thermal energy that moves from warm obj to cool
When hold ice it melts b/c thermal energy is transferred from hand to ice.

UV
Now that we’ve talked about Heat, let’s do a fun
UV activity.

UV Beads!

UV Forecast for Thursday, April 23