7th grade ch. 1 sec. 2 convection currents & the mantle
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YouTube video-Bill Nye Heat
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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)
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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.
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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
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A lava lamp A lava lamp demonstratingdemonstrating
convection in the mantle.convection in the mantle.
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examples of heat examples of heat transfertransfer
conductconductionion
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Convection & Convection & ConductionConduction
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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.
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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.
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What are the What are the three types of three types of heat transfer?heat transfer?
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1.1. RadiationRadiation
2.2. ConductionConduction
3.3. ConvectionConvection
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Describe how Describe how convection convection
currents form.currents form.
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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
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What happens to What happens to convection currents convection currents
when a fluid when a fluid reaches a constant reaches a constant
temperature?temperature?
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When a fluid When a fluid reaches a constant reaches a constant temperature, the temperature, the
convection convection currents stop.currents stop.STO
P