1. Chapter 7
Energy & Its Forms

2. What is Energy Energy: the ability to do work
Energy is transferred by a force over a distance
Also measured in Joules

3. Types of Energy Kinetic Energy: “energy of motion”
Potential Energy: “stored energy”

4. Kinetic Energy Anything in motion has kinetic energy
Depends on an objects mass and velocity
KE = ½ mv2
SI Unit: Joule

5. Potential Energy Depends on the objects position and mass
Gravitational Potential Energy: depends upon an object’s height
GPE = mgh
SI Unit: Joule

6. Forms of Energy There are 6 main forms of energy. Heat Mechanical
(sound)
Electromagnetic
(light)
Chemical
Nuclear
Electrical

7. Mechanical Energy Energy associated with motion
Examples: waterfalls, speeding trucks, sound, wind

8. Thermal (Heat) Energy
Energy associated with the internal motion of atoms
The faster the atoms move…the more thermal energy
Causes temperature changes & phase changes (solid-liquid-gas)

9. Chemical Energy Energy stored in chemical bonds in compounds
Examples: digestion, fuel for a car, burning wood

10. Electrical Energy Energy associated with electrical charges.
Example: Lightning

11. Electromagnetic Energy
Energy that travels through space in the form of waves
Examples: visible light, X-rays

12. Nuclear Energy Energy stored in the nucleus of the atom
Nuclear fission: energy released when nuclei are split
Nuclear fusion: energy released when nuclei are combined

13. Energy Conversion & Conservation

14. Law of Conservation of Energy
States that:
Energy cannot be created or destroyed
Energy can only be converted from one form to another

15. Energy Conversion (Pendulum)
KE = zero
PE = maximum
KE = zero
PE = maximum
KE = maximum
PE = zero

16. Energy & Mass
Albert Einstein discovered the relationship between energy and mass in 1905.
The equation E = mc2 shows that mass and energy can be converted into each other
c= speed of light (3 x 108 m/s)

17. Energy Resources

18. Types of Energy Resources
Nonrenewable energy resources:
Exist in limited quantities
Once used, they cannot be replaced quickly or easily (only over millions of years)
Renewable energy resources:
Relatively unlimited
Can be replaced in a shorter period of time

19. Nonrenewable Energy Resources
Fossil Fuels: formed underground from the remains of once-living organisms
Relatively inexpensive, but create pollution & are limited in quantity
Examples: Oil, natural gas, coal

20. Renewable Energy Resources
Hydroelectric: energy from flowing water
Solar: usable energy from sunlight
Geothermal: energy from the heat beneath
Earth’s surface (steam)
Other: Biomass, Hydrogen fuel cell, wind