Download LT 2 Heat Transfer Extra Practice

Name: _____________________________________________
Period: ______
Earth’s Interior
Directions:
Read (re-read) the following information. Use the information in the reading to complete the following
questions. Upon completing this assignment you will be allowed to reassess Learning Target (LT) 2: Heat
Transfer.
Heat is transferred to the surface of the Earth from the hot Earth's core by conduction and from
radiation from the Sun. The atmosphere is heated by absorption of some of the
electromagnetic radiation from the Sun, and contact with the warm surface of the land and
water. The warm land and water also radiates infrared, some of which is absorbed by the
atmosphere, adding to its thermal energy. The remaining heat on the surface is sent out into
space in the form of infrared radiation.
So what causes the plates to move? It turns out to be a consequence of the high temperatures
inside Earth. Common experience tells us that heat flows from hot to cold, so the heat in Earth's
deep interior must be flowing somehow to the surface. Hot lavas and gases coming out of
volcanoes are direct evidence of heat flowing out of Earth. Another indicator of heat flow is the
increase in temperature with depth inside deep mines. These measurements of heat flow,
however, are all made near the surface. The processes by which heat moves in Earth's deep
interior are investigated by computer simulations, which can be compared with seismic and
heat flow data that show temperature variations in Earth's interior.
Both measurements and simulations show that the hottest part of Earth's interior is the iron
core. Part of the heat down there is actually left over from the fiery formation of Earth; part is
from latent heat released by the freezing of liquid iron in the outer core onto the solid inner
core, and part is (possibly) from the slow decay of naturally radioactive elements like uranium
and potassium mixed in the core.
The core heats the bottom of the rocky mantle. The hottest rock near the bottom of the mantle
becomes slightly less dense than the somewhat cooler rock above it, so buoyancy forces try to
push the hottest rocks upward. Although the rock in the mantle is solid, the pressures and heat
are so great that the rock can deform slowly, like hot wax. So the hot rock creeps upward
through the cooler rock. As the hot rock rises, cooler rock flows downward to take its place next
to the core, where it is heated and becomes buoyant enough to rise again later.
The rising hot rock comes in contact with cold rocks near the surface of Earth where it gives off
its heat, cools, and sinks again. Most of the rock in the mantle moves in this broad cyclic flow,
indicated by the arrows in the figure. This zone, where rock is soft enough to flow, is called the
asthenosphere. This means of heat transport--the cyclical movement of hot and cold material-is called convection.
Occasionally, however, masses of hotter-than-normal rock rise independently of the broad
flow, like bubbles through a flowing stream. These masses of very hot rock form rising columns
with rounded tops, called plumes.
Rock near the surface of Earth is so cold and at such low pressures that it cannot flow like
mantle rock. So how does heat get through this rigid layer lithosphere, to the surface? At the
top of the asthenosphere, the hot rock flows along the bottom of the lithosphere, transferring
its heat to the cold rocks by conduction. The heat then flows through to the surface, again by
conduction.
A second way of getting heat through the lithosphere is more exciting: melt some of the mantle
rock and let it flow through cracks in the lithosphere to the surface! Sound familiar? Places
where liquid rock (lava) flows onto Earth's surface are usually called volcanoes!
Describe what direction heat get transferred from one object to another.
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What are the three ways in which heat is transferred from one object to another?
1.
2.
3.
Earth has an internal and an external heat source.
What is Earth’s external heat source? ______________________________________________
How does the energy from this source reach the Earth? (circle the appropriate answer/s)
Conduction
Convection
Radiation
What is Earth’s internal heat source? _______________________________________________
How does the energy from the inner core reach the outer core? (circle the appropriate answer/s)
Conduction
Convection
Radiation
How does the energy from the outer core reach the mantle? (circle the appropriate answer/s)
Conduction
Convection
Radiation
How does the energy from the outer core travel through the mantle? (circle the appropriate answer/s)
Conduction
Convection
Radiation
How does the energy from the mantle reach the crust? (circle the appropriate answer/s)
Conduction
Convection
Does the crust only receive heat from the mantle?
Radiation
Yes
No
Explain your thinking. ___________________________________________________________
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Comments: __________________________________________________________________
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