1. Heat Transfer and Nuclear Reactions
Unit 11: Forces & Energy

2. Thermodynamics
The study of how heat moves

3. Heat Transfer Heat moves from HOT to COLD
Insulators slow down heat transfer
Conductors easily allow heat transfer

4. Heat Transfer
Heat transfer continues until BOTH objects are in Thermal Equilibrium.
This means that both objects are at the SAME TEMPERATURE!

5. Heat Transfer There are 3 types of Heat Transfer Conduction Convection
Radiation

6. Heat Transfer
Conduction - Heat transfer through objects that are touching each other
Example: Metal spoon in hot pot

7. 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.

8. 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.

9. Convection Currents

10. Convection Currents

11. Convection Currents
Much of Earth’s climate is regulated by giant convection currents in the ocean

12. Heat Transfer Radiation - Heat transfer through electromagnetic waves.
Examples: Sun warms the Earth; standing far from a fire but feeling the warmth

13. Nuclear Reactions
In chemical reactions electrons are transferred or shared between atoms.
Nuclear reactions involve changes in ATOMIC NUCLEI.

14. 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.

15. 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

16. 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.

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