TOPIC: HeatAIM: How is heat transferred?

What isheattransfer?

•Movement of heat from warm cool object

•Example = hot pan

•Heat moves from pan handle

3 types of heat transfer

1.Conductio

n

•Heat transfer in SOLIDS

•Heat transfer by the direct contact of molecules

Fast moving molecules (have more heat) Bump into slower ones Start to move faster collide with other slower molecules…

Why can the girl on the right toast marshmallows without

getting burned?

Conductor

•Material that allows heat to move through it easily

•Metals (copper & silver are the best)

•Example: copper pipes

(Heat exchangers in hot water tanks, under floor heating systems, and car radiators)

TOPIC: HeatAIM: How is heat transferred? Cont’d…

Insulators•Do not conduct heat easily

•Wood, paper, wax, air, house insulation, plastic

2.Convectio

n

•Transfer of heat in liquids & gases

•Liquid heated molecules move faster & farther apart

•less dense rise carrying heat with it

•Example: warm air rises, cool air sinks

Convectioncurrents

•Up & down movement of molecules due to changes in density

Convection Currents Inside the Earth

3.Radiation

•Heat transfer through space

•Can travel when no matter is present (vacuum)

•Heat energy from sun, stars, fire

Radiation from the Sun travels through empty space.

Radiation from the fire heats the marshmallow.

SOLIDS

LIQUIDS & GASES

THROUGH SPACE

A

B

C

conduction

radiation

convection

REVIEW

A

B

D

convection

radiation

conduction

REVIEW

C convection

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