1. Mr. Clark Bethpage HS AP Environmental Science
Energy Basics
Mr. Clark
Bethpage HS
AP Environmental Science

2. Energy Basics Energy Work Power First Law of Thermodynamics
Second Law of Thermodynamics
Kinetic energy
Potential energy

3. Energy Basics First Law Efficiencies Second Law Efficiencies
Thermal efficiency
Electrical resistivity
Conservation
The hard path versus the soft path

4. Energy Energy is the ability to do work.
Energy is measured in units called Joules.
Energy is also measured in calories, BTUs, and ergs.

5. Electromagnetic Spectrum

6. Transfer of Energy Convection Conduction Radiation
Heat from a stove burner causes
atoms or molecules in the pan’s
bottom to vibrate faster. The vibrating
atoms or molecules then collide with
nearby atoms or molecules, causing
them to vibrate faster. Eventually,
molecules or atoms in the pan’s
handle are vibrating so fast it
becomes too hot to touch.
As the water boils, heat from the hot
stove burner and pan radiate into the
surrounding air, even though air
conducts very little heat.
Heating water in the bottom of a pan
causes some of the water to vaporize
into bubbles. Because they are
lighter than the surrounding water,
they rise. Water then sinks from the
top to replace the rising bubbles.This
up and down movement (convection)
eventually heats all of the water.

7. Energy Quality

8. Work Work is force times distance. W = F x d
The unit of work is a Newton-meter.
A Newton-meter is called a Joule (J).

9. Power Power is the rate that energy is used.
Power is equal to work / time.
P = W/t
One joule / second is a watt.
Electrical Power can also be calculated by another formula.
Electrical Power = voltage x current.
P = V x I watts = volts x amps

10. First Law of Thermodynamics
Energy is neither created nor destroyed but is always conserved and transformed from one kind to another.
Energy only changes form.
You cannot get something from nothing.
Energy in = energy out

11. Second Law of Thermodynamics
Energy always goes from a more usable form (high quality) to a less usable form. (low quality)
All systems move to maximum entropy.

12. Kinetic Energy Kinetic energy is the energy of motion.
KE = ½ mv2 where m is mass and v is velocity.

13. Potential Energy Potential energy is stored energy.
PE = m x g x h where m is mass, g is the acceleration due to gravity, and h is height.

14. First Law Efficiencies
First Law Efficiencies are the amount of energy available without consideration of energy quality.

15. Second Law Efficiencies
Second Law Efficiencies are the amount of energy available with consideration of energy quality.

16. Thermal efficiency
Thermal efficiency is the maximum possible efficiency of a heat engine. (Carnot 1824)

17. Electrical resistivity
Electrical resistivity is what causes electrical energy to be converted to heat energy.
It is like electrical friction.

18. Conservation
Conservation is saving energy whenever possible.

19. The hard path vs. the soft path
Develop alternate energy technologies such as solar, wind, and biomass.
Use diverse technologies.
Be flexible with the use of technologies.
Match the needs of the area.
Hard Path
Let energy companies develop resources.
Do away with regulations so that the market can determine the most efficient use of energy with the least environmental consequences.