Heat Transfer and
Nuclear Reactions
Unit 11: Forces & Energy
Thermodynamics
•The study of how heat moves
Heat Transfer
• Heat moves from HOT to COLD
• Insulators slow down heat transfer
• Conductors easily allow heat
transfer
Heat Transfer
• Heat transfer continues until
BOTH objects are in Thermal
Equilibrium.
• This means that both objects are at
the SAME TEMPERATURE!
Heat Transfer
• There are 3 types of Heat Transfer
• Conduction
• Convection
• Radiation
Heat Transfer
• Conduction - Heat transfer through
objects that are touching each other
Example: Metal spoon in hot pot
Heat Conduction
When you heat a metal strip at one end, the heat travels to the other end. As
you heat the metal, the particles vibrate, these vibrations make the adjacent
particles vibrate, and so on and so on, the vibrations are passed along the
metal and so is the heat.
Heat Transfer
• Convection - Heat
transfer through
matter by moving
currents in liquids
or gases
Examples: Hot air rises, cold air
falls creating wind in storms;
currents in heated water.
Convection Currents
Convection Currents
Convection Currents
• Much of Earth’s climate is regulated by
giant convection currents in the ocean
Heat Transfer
• Radiation - Heat transfer through
electromagnetic waves.
Examples: Sun warms the Earth; standing far
from a fire but feeling the warmth
Nuclear Reactions
• In chemical reactions electrons are transferred or shared
between atoms.
• Nuclear reactions involve changes in ATOMIC NUCLEI.
Nuclear Fission
• FISSION is a nuclear reaction that occurs when a large nucleus is
bombarded with a small particle, a neutron, and it splits into
smaller/lighter nuclei.
• Nuclear power plants are powered by nuclear fission reactions to generate
electricity.
• Uranium-235 is the typical fuel for nuclear fission reactions.
• A CHAIN REACTION is a self-sustaining reaction (without outside
influence) in which neutrons released in fission produce an additional
fission – process repeats.
Nuclear Reactions
• Draw a sketch of this FUSION Nuclear Reaction
• What are the reactants in the nuclear reaction above?
• Deuterium & Tritium, both isotopes of Hydrogen
• What is the main product of this nuclear reaction?
• ENERGY and Helium
• Is Helium radioactive?
• NO
Nuclear Fusion
• FUSION is the process that powers the Sun
(stars).
• In this reaction two hydrogen atoms combine (fuse) to form a
larger/heavier atom of helium.
• A Nuclear Fusion Reaction needs extreme heat and pressure like
that of the Sun to occur.
Heat Transfer?
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