1. THERMAL ENERGY AND HEAT
With credit to Jennefer Cardenas

2. Objectives
Students will be able to identify and know differences between THERMAL ENERGY, TEMPERATURE, and HEAT and how heat energy is produced.
Students will be able to tell how heat changes matter structurally
Students will be able to identify the 3 ways heat is transferred: conduction, radiation & convection
Students will be able to compare different conductors and insulators.
Students will be able to measure temperature and compare the Celsius and Fahrenheit scales.

3. HEAT ENERGY
Heat energy is produced by the motion of particles (atoms or molecules) in matter.
Since heat is energy it can do work.
A Heat Source is the place from which heat energy comes.
Sources include the Sun (most impt), from motion (ME) like friction, chemicals, electricity, nuclear (in the atom) fusion & fission.

4. Nuclear Fusion & Fission
Fission: Occurs when atoms split, forming atoms of new elements, giving heat & light E.
Fusion : Occurs when atoms are forced together (in stars) to fuse, giving off E.

5. TEMPERATURE & KINETIC THEORY
Is a measure of average kinetic energy of the individual particles in an object.
Kinetic Theory: Matter is made up of tiny particles: atoms & molecules. These are always in motion even if the larger object isn’t moving. The faster the particles are moving, the more KE they have.

6. THERMAL ENERGY IS the TOTAL energy of ALL the particles.
If 2 samples of matter are at the same temperature they do not necessarily have the same total energy.

7. Diffusion DEMO
Get 2 beakers of water, one room temp, one cold and one hot. Put a drop of food dye in each, right in the middle & observe movement of dye.
Why did the dye move the way it did in each water temp? The answer has to do with the different temperatures.

8. Explanation
Using the Kinetic Theory of Matter, explain the motion of the dye in the different water temperatures.
Higher temps = more total KE
More KE = more motion of the particles
The more the molecules are moving, the more collisions there are between the dye particles & the water molecules
The more collisions, the faster the dye will spread.

9. Changes in Heat Affecting Mass (L2)
As heat is applied to a mass, total KE increases so temp increases. Particles move faster.
Every substance has a melting (solid to liquid) and vaporization (liquid to gas) point. Physical characteristic of identification.
As a substances heats, its particles move faster until they eventually break bonds and escape (vaporization).
As a substances cools, its particles move slower, moving closer together & freeze into a solid.

10. As substances heat, they expand
As substances cool, they condense
Except for WATER, only substance on Earth that expands when it freezes (as it shifts into a crystal lattice structure & molecules become more spread out).

13. Temperature Scales
Formulas: F = 9/5 C + 32 C = 5/9 (F – 32) Kelvin (heat scale) Absolute 0 – NO atomic motion K = C Interactive Thermometer

14. What is Heat? How is heat transferred?
Heat is thermal energy moving from a warmer object to a cooler object. These processes act to equalize temperature differences within a system.
There are 3 ways that heat can move.
Conduction
Convection
Radiation

15. CONDUCTION
Heat or thermal conduction is transfer of thermal energy thru matter, from a region of higher to a region of lower temperature Also described as heat energy transferred from one material to another by direct contact.

16. CONVECTION
Convection is the movement of molecules within fluids ( a liquid or a gas); the warm fluid rises and cooler fluids flow in to replace it. This creates a circular flow.

17. More Convection
The wind we feel outside is the result of convection currents.
Warm air is less dense than cold air, so it rises.
During the daytime, cool air over water moves to replace the air rising up as the land warms the air over it. During the nighttime, the directions change -- the surface of the water is sometimes warmer and the land is cooler.

18. RADIATION The transfer of energy by electromagnetic waves.
Radiation does not require matter to transfer thermal energy.

19. Radiation
Sun’s energy warms the earth & powers photosynthesis thru radiation.
The sun's rays travel in straight lines at various wavelengths.
When sunlight hits the earth, its radiation is absorbed or reflected.

20. Conductors and Insulators
A conductor is an object that can carry heat well
Good conductors are metals like copper. These also conduct electricity as well as thermal energy.
An insulator is an object that carries heat poorly
Examples are shredded paper, styrofoam, air, water, etc.

21. CHECK YOURSELF Name the 3 ways heat is transferred? TRUE or FALSE
The transfer of energy by electromagnetic waves is the definition for convection
In this picture “B” is representing a heat conductor and “A” is representing heat convection.