QuestionIf a cup of coffee and an ice cream cone were left on

the table in this room what would happen to them? Why?

The cup of coffee will cool until it reaches room temperature. The ice cone will melt and then the liquid will cool to room temperature.

What is Heat?This is the movement of

thermal energy from a substance at a higher

temperature to another at a lower temperature.

Heat vs. Temperature

Heat is the actual energy…

Temperature is the measure of average kinetic energy of particles in a

substance.

Heat is NOT Temperature

Heat TransferHeat TransferHeat always moves from a warmer place to a Heat always moves from a warmer place to a

cooler place.cooler place.

Hot objects in a cooler room will cool to room Hot objects in a cooler room will cool to room temperature.temperature.

Cold objects in a warmer room will heat up to Cold objects in a warmer room will heat up to room temperature.room temperature.

Heat Transfer MethodsHeat transfers in three ways:

ConductionConvectionRadiation

Conduction Conduction heat transfer is the flowing of heat

energy from a high-temperature object to a lower-temperature object. Must have contact (touch)

EXAMPLE OF CONDUCTIONA piece of cheese melts as heat is transferred from the

meat to the cheese (Contact)

Have you ever…Touched a metal spoon sitting in a pan of boiling

water only to be surprised by HOW hot it is??

Think back to what you know about metals and nonmetals. What conducts heat better, metal or nonmetal? Why?

When you heat a metal strip at one end, the heat travels to the other end.

As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on and so on, the vibrations are passed along the metal and so is the heat. We call this? Conduction

The outer e______ of metal atoms drift, and are free to move.

When the metal is heated, this ‘sea of electrons’ gain k_____ energy and transfer it throughout the metal.

Insulators, such as w___ and p____, do not have this ‘sea of electrons’ which is why they do not conduct heat as well as metals.

lectrons

inetic

ood lastic

Metal is a conductor, wood is an insulator. Metal conducts the heat away from your hands. Wood does not conduct the heat away from your hands as well as the metal, so the wood feels warmer than the metal.

ConvectionConvection takes place when heated molecules move

from one place to another, taking the heat with them. Convection is common in both the atmosphere, as

well as in the oceans. Convection = VENTS

Convection is the primary way that heat moves through gases and liquids.

Convection

CONVECTION• Convection is the movement that transfers heat within

fluids and air (gas)• Heat is transferred by currents within the fluid or gas

• Convection = VENTS (through air and liquid particles)

• Convection moves in a circular pattern

Examples of Convection:Have you ever noticed that the air near the ceiling is

warmer than the air near the floor? Or that water in a pool is cooler at the deep end?

Examples: air movement in a home, pot of heating water.

What happens to the particles in a liquid or a gas when you heat them?

The particles spread out and become less dense.

Hot water rises

Cooler water sinks

Convection current

Cools at the surface

Where is the freezer

compartment put in a fridge?

Freezer compartmen

t

It is put at the top, because cool air sinks, so it cools the food on the way down.

It is warmer at the

bottom, so this warmer

air rises and a

convection current is

set up.

How does heat energy get from the Sun to the Earth? There are no particles

between the Sun and the Earth so it CANNOT travel by conduction or by convection.

?RADIATION

RADIATIONRadiation is the transfer of energy by electromagnetic

wavesRadiation does NOT require matter to transfer thermal

energyRadiation = Radiates (heat escaping the sun)

Examples of RADIATION

1. Fire

2. Heat Lamps

3. Sun

Radiation travels in straight lines

True/False

Radiation requires particles to travel

True/False

Radiation travels at the speed of light

True/False

Radiation The transfer of energy by electromagnetic waves.

Examples:

SunFireLight bulb

Why are houses painted white in hot countries?

White reflects heat radiation and keeps the house cooler.

Example of Conduction

Think of a metal spoon in a pot of water being heated.

The fast-moving particles of the fire collide with the slow-moving particles of the cool pot.

Because of these collisions, the slower particles move faster and heat is transferred.

Then the particles of the pot collide with the particles in the water, which collide with the particles at one end of the spoon.

As the particles move faster, the metal spoon gets hotter. This process of conduction is repeated all along the metal until the entire spoon is hot.

1. Which of the following is not a method of heat transfer?

A. Radiation

B. Insulation

C. Conduction

D. Convection

2. In which of the following are the particles closest together?

A. Solid

B. Liquid

C. Gas

D. Fluid

3. How does heat energy reach the Earth from the Sun?

A. Radiation

B. Conduction

C. Convection

D. Insulation

4. Which is the best surface for reflecting heat radiation?

A. Shiny white

B. Dull white

C. Shiny black

D. Dull black

5. Which is the best surface for absorbing heat radiation?

A. Shiny white

B. Dull white

C. Shiny black

D. Dull black

3 Ways Energy (Heat) is Transferred

*Transferred in rays or waves

*Energy from the Sun warms the Earth

Example:

Sentence:

Example:

Sentence:

Example:

Sentence:

*Transfer of heat (energy) that happens when molecules bump into each other

*Objects must be touching

*”Conduction is touchin’”

*Transfer of heat by the flow of material

*In warm air, the molecules move apart, so it is less dense and rises

*In cooler air, the molecules move closer together, so it is more dense and sinks

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