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# By Marvin Lowe - PowerPoint PPT Presentation

By Marvin Lowe. Teacher ' s Notes. Subject: Physics (Heat Energy) Topic: Conservation of energy- Heat transfer Grades: 8 Prior Knowledge: 1) phases of matter- solid, liquid, gas, plasma 2) phase changes- solid to liquid, liquid to gas, solid to gas, liquid to solid, gas to liquid

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Presentation Transcript

Teacher's Notes

Subject: Physics (Heat Energy)

Topic: Conservation of energy- Heat transfer

Prior Knowledge:

1) phases of matter- solid, liquid, gas, plasma

2) phase changes- solid to liquid, liquid to gas, solid

to gas, liquid to solid, gas to liquid

3) molecules, elements, metals, nonmetal

4) density- molecule spacing of solid liquid and gas

5) buoyancy

By the end of this lesson student’s should be able to

explain how heat and temperature are due to

molecular motion and how energy is transferred

define and explain the three types of heat transfer

compare conductors and insulators

Motion can produce heat. The amount of heat produced depends on  the amount of motion. A molecule at any temperature is the same size.

Matter is made of atoms and molecules, which are always in motion.  The speed of the molecules depends on how much energy they  have, which affects the state of matter they are in – solid, liquid, gas  or plasma. The less energy the particles have the less they move  and the more solid and colder the matter is. The more energy the  particles have the more they move so the more liquid or gaseous  and hotter the matter is.

Heat is a form of energy caused by the friction between molecules due to the internal motions of molecules. Heat transfer is heat energy moving from a warmer object to a cooler object.

There are three types of heat transfer:

1) Conduction is heat transferred by the direct contact of molecules.

2) Convection is heat transferred through a liquid or gas by means of    up-and-down movements called convection currents.

3) Radiation is heat transferred through empty space by invisible

infrared rays.

Touch each image and discuss.

Motion causes friction which produces heat. The  amount of heat produced depends on the

amount of motion and friction.

Touch each image to view the different  energy levels of the molecule.

Water is made of molecules. Molecules are always in motion.  The more molecular motion and friction the more heat. The  energy level of the molecules determines their state of matter.

Touch each image to see how the water  molecules react.

Heat is a form of energy caused by the internal motion of molecules and friction as the molecules rub against each other.  The hotter a substance is, the faster the molecules are moving.

Drag the hand over the ice or pan, observe  the heat transfer for each.

Heat transfer is when heat energy moves from a warmer object to a cooler object.

Drag the terms to the correct definitions.

Conduction

heat transferred by the direct contact of molecules.

Convection

heat transferred through a liquid or gas by means

of up-and-down caused by differences in temperature and density.

heat transferred through empty space by invisible

infrared rays.

Conduction

heat transferred by the direct contact of molecules.

Convection

heat transferred through a liquid or gas by means

of up-and-down.

heat transferred through empty space by invisible

infrared rays.

Touch the image.

Conduction is the transfer of energy  through matter by direct contact of particles.

Can you think of objects that are used to conduct heat or energy?

Metal pots and pans

conduct heat to cook food.

Copper wire conducts

energy.

Can you think of objects that are used to stop the conduction  of heat or energy?

Insulators are substances that do not conduct heat and   energy  well. Cloth, wood, glass, plastic, and rubber   conduct energy and heat very slowly when in contact   with vigorously moving particles of a hot object.

A winter coat stops energy from

being conducted out of a body.

from a hot pan to the hand.

Drag the objects to connect the battery to the light  bulb. Find out which items conduct energy.

Click on the red molecule to view the  4 stages of convection.

Convection is heat that is transferred in liquids or gases by means of

up and down movements of matter. The hot molecules move up and

the cold molecules move down. Cycles are created

called convection currents.

Touch each image to see examples of heat  radiation.

Radiation is the heat energy that is transferred   through empty space by invisible infrared radiation.

Drag the correct answer to match definition.

1) Energy caused by motion of particles in matter.

Heat

2) Tiny particles that make up matter.

Molecules

3) Movement of heat from a warmer to a cooler object.

Heat Transfer

Heat

Heat Transfer

Molecules

Drag the correct answer to match definition.

1) Movement of heat by direct contact.

Conduction

2) Movement of heat that is transferred through

empty space.

3) Movement of heat in an up and down motion

of particles that occurs in liquids and gases.

Convection

Conduction

Convection

Drag the correct answer to match  the example.

1) Bacon cooking in a pan.

2) Air above a grassland plain warming up in

the sun causing violent updrafts that lead to

3) The warmth of a fireplace heating a person

in a room.

Convection

Conduction

1) Convection

2) Conduction

Why should the handle of a pot be made of  wood or plastic rather than metal?

1

A

They are good conductors of heat.

B

They are poor conductors of heat.

2 rather than metal?

What happens to molecules as they heat up?

A

They burn up and stop moving.

B

They move less vigorously.

C

They move more vigorously.

D

No change occurs.

What happens to molecules as they begin to rather than metal?

cool?

4

A

They freeze and stop moving.

B

They move less vigorously.

C

They move more vigorously.

D

No change occurs.

5 rather than metal?

Cold air is more dense than hot air?

A

True

B

False

What is the correct order of a  convection current? rather than metal?

6

A

rises, heats up, sinks, cools

B

sinks, cools, rises, heat ups

C

heats up, cools, rises, sinks

D

heats up, rises, cools down, sinks

7

A

convection

B

conduction

C