Guided Note

Taking

Matter in Motion• All matter is made up of particles

• All particles are constantly moving

• You know that moving things have kinetic energy

• The faster something moves, the ______ kinetic energy it has

• Temperature is a measure of the average kinetic energy that the particles of “something” has

more

MEASURING TEMPERATURE

EXAMPLE:

Every time a molecule of air strikes the thermometer, it transfers kinetic energy to the molecules of liquid inside the thermometer. As the temperature of the air rises, ____ collisions happen per second. As the ______ energy of the liquid inside the thermometer increases, the liquid rises in the thermometer.

morekinetic

Temperature ScaleThere are two main temperature scales used in science: Celsius and

________Celsius is a relative scale (has negative numbers). It is based on two

things:1. Freezing point of water2. Boiling point of water

Kelvin is an __________ scale (no negative numbers). Based on absolute zero.

Absolute zero is the coldest temperature a material may ever have. At absolute zero, a material’s particles have no motion (zero ________ energy). This temperature is theoretical and can never be obtained.

CONVERSION FORMULAS:Celsius Kelvin: oC+273 example: 0oC=273 KKelvin Celsius: K-273 example: 350K=77oC

Kelvin

absolute

kinetic

Practice Problems

• 55oC = ____K

• 134oC = ____K

• 100K = ____oC

• 375K = ____oC

328

407

-173

102

Heat

• Heat refers to the energy transferred between two objects at different temperatures when they interact with each other.

• An object does not “contain” heat.

• ________ is transferred as heat

• Energy is always transferred from the substance at a higher temperature to the substance at a lower temperature

Higher Temperature → Lower Temperature Heat

Energy

More about Heat

• Heat is measured in ______

• Like work, heat involves transfer of energy.

• Heat is energy transferred between objects at different temperatures.

• Work is energy transferred when a force acts over a distance.

Joules

Thermal energy is the total energy of the particles in a material. This total includes both ______ and ________ energy. The kinetic energy is due to vibrations and movement within and between particles. The potential energy is determined by forces that act within or between the particles.

Example: the change seen in melting ice cream due to a hot spoon resting on it is caused by the flow of thermal energy from the spoon.

kineticpotential

Conductors

• A conductor is a material through which _____ can be easily transferred as heat

– Good conductors:• Metals, such as copper and silver

– Poor conductors:• Gases are extremely poor conductors (particles

are far apart)• Liquids are also poor conductors, but they are

better than gases• Some solids like rubber and wood

energy

Insulators

• An insulator is a material that is a poor energy conductor; it does not transfer energy as heat easily– Good insulator examples:

Wood Wool

Energy Transfer

• We’ve just learned about heat, the transfer of energy from particles of one object to those of another object due to temperature differences.

• There are actually ______ ways to transfer energy.

THREE

• When two objects or substances come into contact with each other, this is called

____________

• Write down the definition:Conduction is the transfer of energy as heat between particles as they touch.

CONDUCTION

What are some examples?

Burning your hand on a hot stove

Ice cube melting in your mouth

Other types of Energy Transfer

• Think about sitting by a campfire. You don't touch the flames, but you get warmed. How does this happen?

• There are actually two types of energy transfer happening here.

• The first is called»convection

The air closest to the fire becomes warm and expands. What is happening when the air gets warmer is that its particles are getting further a p a r t. This makes the airless dense and it rises.When it rises, it carries the extra energy with it. The space the hot air left behind is replaced with cooler air. This air becomes hot by the fire and expands and rises as well. This is an example of convection.

Write down the definition:

• Convection is the transfer of energy by the movement of gases or liquids

• Convection involves the movement of the heated substance itself.

What are some examples?

Water boiling in pot

Convection cell in Earth’s mantle

• As you stand close to the campfire, you can feel its warmth, even if you are not in the path of the heated air.

• In this case, the energy is being transferred by

radiation

• Radiation differs from convection and conduction in that it does not involve the movement of matter. The energy is transferred in the form of electromagnetic waves. You will learn more about electromagnetic waves in future science classes.

• Radiation is the only form of energy transfer that can occur in a vacuum (where there are no particles), such as outer space.

Write down the definition:• Radiation is the transfer of energy by

electromagnetic waves

• You can feel radiation, but you can’t see it!

• Examples of radiation:– Energy transferred from the sun– Standing near a fire– Radiation therapy to kill cancer

Summary of Energy Transfer

There are three types of energy transfer:

• Conduction involves objects in direct contact

• Convection results from the movement of warm fluids

• Radiation does not require physical contact between objects

Thermal Pollution

• Have you ever noticed that the city feels hotter on a warm day?

• Heat removed from the air-conditioned buildings and vehicles is released into the outside air

• Much of the energy used in everyday life – electrical, chemical, mechanical, radiant, or nuclear – ends up as waste thermal energy that is given off to the surroundings.

• Sometimes the level of heat released can reach unhealthy levels.

• When waste heat significantly changes the temperature of the environment, we call this ________________.

• Thermal pollution is a particular problem in places where power plants and factories use water to cool their equipment.

Thermal pollution

• If the warmed water is dumped into a river, lake, or ocean, the higher temperature can ______the dissolved oxygen content and can cause serious problems for the plants and animals living in the water.

• The higher temperature can alter the reproductive processes of the plants and animals and in some cases KILL the fish and plants living in the water.

lower

Think about your morning routine

• Do you take a shower?

• Do you use hair products?

• Do you eat cereal?

• Do you drink milk?

• Etc.

Everything requires energy

• The water needed to be heated• The products needed to be produced• The plastic bottles needed to be manufactured• The cereal was produced, so was the bag that

keeps it fresh, and the box that it sits in.

All this happens in power plants and factories

Other Options

• Thermal pollution can be reduced by releasing small amounts of warm water mixed with plenty of cooler water.

• In order to do this, companies must build expensive _______________.

• These towers cool the water by fans or evaporation.

Cooling towers

• Since these towers are expensive, businesses may have to raise the prices for the products they make. Which means that you have to pay more.

• Some people think that the government puts unnecessary laws and regulations on businesses to build expensive cooling devices.

• Some people think that it is our responsibility to prevent damage to the environment.

What do you think?

• The temperature of water discharged from a power plant ranges from 5-11oC.– A change of 0-2oC = excellent– A change of 2.2-5oC = good– A change of 5.1 – 9.9oC = fair– A change of >10oC = poor

Should we regulate the energy dischargeand pay more? Is it necessary?