YouTube video-Bill Nye Heat

Heat transferHeat transfer movement of energy from warmer object movement of energy from warmer object cooler object cooler object 3 types3 types::

1.1.

radiatioradiationn

thru. empty spacethru. empty space

nono direct contact direct contact

2. 2. conducticonductionon

by direct contactby direct contact

3. 3.

convecticonvectionon

movement of a heated movement of a heated fluid fluid (liquids & gases)(liquids & gases)

convection convection currents:currents:

flow that transfers heat within a fluidflow that transfers heat within a fluid form by:form by:

changes in a fluid’s density

force of gravity

heating &cooling of a fluid

When a fluid is heated, its density decreases.

When a fluid cools, its density increases.

Convection in Earth's Convection in Earth's MantleMantle

Heat from Earth’s core & mantle Heat from Earth’s core & mantle

cause convection currents to form cause convection currents to form

in asthenosphere in asthenosphere Hot columns of mantle rise thruHot columns of mantle rise thru

asthenosphere asthenosphere At top of asthenosphere, hot material At top of asthenosphere, hot material spreads out spreads out Pushes cooler material out of way Pushes cooler material out of way Cooler material sinks back into Cooler material sinks back into asthenosphereasthenosphere

A lava lamp A lava lamp demonstratingdemonstrating

convection in the mantle.convection in the mantle.

examples of heat examples of heat transfertransfer

conductconductionion

Convection & Convection & ConductionConduction

In conduction, the heated particles of a substance In conduction, the heated particles of a substance transfer heat to other particles through direct transfer heat to other particles through direct contact.contact.

Remember:Remember: HeatHeat goes goes higherhigher..

Hot air, hot water, and hot rockHot air, hot water, and hot rock

all tend to rise.all tend to rise.

ColdCold creepscreeps lower. lower. Cold air, cold water, and cool Cold air, cold water, and cool

rock rock

all tend to sink.all tend to sink.

What are the What are the three types of three types of heat transfer?heat transfer?

1.1. RadiationRadiation

2.2. ConductionConduction

3.3. ConvectionConvection

Describe how Describe how convection convection

currents form.currents form.

1.1. The heating and cooling of The heating and cooling of a fluida fluid

2.2. Changes in a fluid’s densityChanges in a fluid’s density

3.3. Force of gravity combine Force of gravity combine to set convection currents to set convection currents in motionin motion

What happens to What happens to convection currents convection currents

when a fluid when a fluid reaches a constant reaches a constant

temperature?temperature?

When a fluid When a fluid reaches a constant reaches a constant temperature, the temperature, the

convection convection currents stop.currents stop.STO

P