1. Energy “The ability to do work.” Only a change in energy is observed.
In other words…
Energy is needed to make something move against a resisting force.
Only a change in energy is observed.

2. Kinds of Energy Electrical energy: Kinetic energy:
in an electrical current.
Kinetic energy:
in motion.
Heat/thermal energy:
random motion of molecules of matter.
Potential energy:
stored energy (may be released = kinetic).
Electromagnetic energy:
travels through empty space.

3. Electromagnetic energy (EME)
Process:
Interacts with matter, changes form, and does work.
Particles moving causes the fields around them to move, thus a wave is produced.
Examples:
visible light, x-rays, UV, infrared, & radio waves.

4. EME & temp.
Since EME is determined by particle movement, temperature may effect this movement:
Hotter object = more movement = greater kinetic energy = greater EME.
Colder object = less movement = greater potential energy = less EME.

5. EME & waves All forms of EME travel in transverse waves:
Waves vibrate at right angles to the direction in which they are moving.
Particles move up and down while the wave passes along the length of the rope.
The wave is traveling through empty space.

6. EMRadiation with the Environment
When electromagnetic waves come into contact with matter, the waves interact with the particles of the material.
Four possible results of this interaction.

7. Interactions: 1) REFRACTED: 2) REFLECTED: water
direction changed as they pass through the material (“bent”).
2) REFLECTED:
waves bounce back/ do not pass through the material.
water

8. Interactions: 3) SCATTERED: 4) ABSORBED:
reflected &/or refracted in various directions.
4) ABSORBED:
energy is taken into the material.

9. Heat & Temperature Temperature:
a measure of the average kinetic energy of the particles of a substance.
KE = temperature.
All matter is made up of particles that are always in motion.

10. Heat & Temp. HEAT: “matter strives for equilibrium:”
hot object into cold object:
KE from hot object transferred to cold object.
The energy that is flowing from one object to another is called HEAT.

11. Heat & Temp. Source: Sink: body or region from which heat is flowing.
body or region into which heat is flowing.

12. Energy Transfer sun 1) RADIATION:
Energy transferred across empty space in the form of electromagnetic waves.
Examples:
light
heat
sun

13. Energy Transfer 2) CONDUCTION:
Heat energy passed from atom to atom or from molecule to molecule through collisions.
Examples: handle of a frying pan:
molecules move faster therefor more collisions...

14. Energy Transfer 2) CONDUCTION (con’t):
Energy able to be transferred through gases, liquids &/or solids.
Most effective

15. Energy Transfer 3) CONVECTION:
Transfer of heat by means of circulatory movements (currents).
Convection currents/cells:
moving masses

16. Heat
How much heat is needed to raise 40 grams of water from 10 dg. to 40 dc.?
#calories =
mass X temp. X spec. heat
40g X 30dc. X 1.0g/cal/dc
= 1,200 calories

17. Specific Heat Definition:
The amount of heat needed to raise the temperature of one gram of any substance by one degree Celsius.
Substances have different specific heats because they heat up at different rates.

18. Specific Heat Example:
how much heat is needed to raise the temp. of 20g of Iron from 20 dg. To 30 dg.?
#cal. = mass X temp. X spec. heat.
# cal. = 20g X 10dc X0.11 ca./g/dc.
# cal. = 22

19. Latent Heat Definition:
Energy absorbed or released by a substance during a change in phase.
Does NOT change temperature.
PE is
KE is

20. Latent Heat Further explanation:
As ice is melting, all of the heat energy being added is used to break up the ice molecules.
None of the heat energy goes into increasing the KE.
This can be seen by taking the temperature.
Until ALL of the ice is melted, temp. = 0 dc.
The only way temp. may rise is if KE is increased.

21. Latent Heat 1) Latent Heat of Fusion: 2 types of Latent Heat:
the amount of energy that was stored during melting, and released during freezing.

22. Latent Heat 2) Latent Heat of Vaporization:
The input of energy during the process of changing from the liquid state to the gaseous state.

23. HEAT ENERGY ADDED (ABSORBED)
Latent Heat
SOLID
HEAT ENERGY GIVEN OFF
HEAT ENERGY ADDED (ABSORBED)
HEAT OF
FUSION
LIQUID
HEAT OF
VAPOR-
IZATION
GAS