1. Unit 3
Energy
and
Work

2. Energy Energy is the ability to do work Energy is all around us
There are two basic kinds of energy

3. The two basic kinds of energy:
Potential energy
Kinetic energy

4. Potential Energy Potential energy is stored energy
There are two types of potential energy
Chemical potential energy
Gravitational potential energy

5. Chemical Potential Energy
Chemical potential energy is energy that can be released as the result of a chemical reaction
Ex. Matches, food, gasoline

6. Gravitational Potential Energy
Gravitational potential energy is also known as energy of position
Gravitational potential energy depends on an object’s weight and height

7. Kinetic Energy Kinetic energy is energy of motion
A moving object has kinetic energy

8. Kinetic Energy Kinetic energy depends on speed and mass
The faster an object is moving, the greater its kinetic energy
The greater an object’s mass, the greater its kinetic energy

9. Forms of Energy There are five main forms of energy Mechanical Energy
Electromagnetic Energy
Heat Energy
Chemical Energy
Nuclear Energy

10. Mechanical Energy
The energy in moving things
Includes sound

11. Electromagnetic Energy
Energy in moving electrons
Includes electricity and light

12. Heat Energy Energy in moving particles of matter
The faster a particle moves, the more heat energy it has
All things contain some heat energy

13. Chemical Energy Energy that holds particles of matter together
Energy in fuel such as wood or coal is chemical energy

14. Nuclear Energy Energy stored in the nuclei of atoms
Heat and light from the sun are produced from nuclear energy

15. Energy Energy can change from one form to another
When energy changes form, some of the energy is always changed into heat energy
Most of this heat energy is lost as waste

16. Thermal Pollution
Thermal pollution is damage that occurs when waste heat enters the environment

17. Conservation of Energy
Law of Conservation of Energy
Energy cannot be made or destroyed, but can only change in form

18. Scientific Theory
A scientific theory is an idea supported by evidence over a period of time
The Law of Conservation of Energy is a scientific theory

19. Matter and Energy E=mc2 Matter can be changed into energy
Energy can be changed into matter
The total amount of matter and energy in the universe does not change
This is explained by the equation:
E=mc2

20. E=mc2
E – energy
m – matter or mass
c – speed of light

21. Work
Work equals force times distance

22. Work Work is done when a force moves an object a certain distance
If an object is not moved, no work is done

23. Work Energy is the ability to do work
However, energy can be used without doing work

24. Work
For work to be done, the direction of the applied force must be the same as the direction of the motion

25. Measuring Work To measure work, you must know: The force in Newtons
The distance in meters
Work can be measured in Newton-meters
(N-m)

26. Joules The metric unit of work is the Joule (J)
1 J (Joule) = 1 N-m (Newton-meter)

27. Measuring Work
When measuring work, you must measure the force applied in the direction of motion

28. Power Power is the amount of work done per unit of time
Power is the rate at which work is done
Power = work / time
Power = (force X distance) / time

29. Power The metric unit of power is the Watt (W)
1 Watt (W) = 1 Joule per second (J/sec)
1 W = 1 N-m/sec
1 W = 1 J/sec

30. Power Large amounts of power are measured in kilowatts (kW)
1 kW = 1000 W