1. Energy

2. Nature of Energy Energy is all around you!
You can hear energy as sound.
You can see energy as light.
You can feel energy as wind.
You use energy when you hit a ball
Energy is involved when electricity flows in a wire

3. Living organisms need energy for growth and movement.

4. What Is Energy? Energy is the ability to do work.
If an object or organism does work, the object or organism uses energy.
Work is done if a force makes something move

5. 6 Energy Types There are MANY types of energy
6 forms of energy are described below:
Mechanical Energy: the energy of moving things
Kinetic Energy: Energy of motion
Potential Energy: stored energy

6. 6 Energy Types (cont.)
Electrical Energy: energy that flows through wires and powers lights and other appliances (the energy of moving charges)
Electromagnetic Energy: the energy of visible light, X-rays, radio waves, microwaves, etc.

7. 6 Energy Types (cont.) Heat Energy: also called thermal energy
if you rub your hands, they become warm
due to moving particles (atoms and molecules) of matter
Chemical Energy: the energy that holds particles of matter together
examples: energy stored in a match, food, fuels, etc.

8. 6 Energy Types (cont.)
Nuclear Energy: the energy stored in a nucleus of an atom
can be released when atoms split or combine
the heat and light from the Sun started as nuclear energy

9. What Is Energy Measured In?
Joules (J)
Same unit as work because the two are so closely related.

10. Vector or Scalar? Energy is a scalar
This means that direction is NOT included

11. Mechanical Energy
When work is done to an object, it acquires energy known as mechanical energy.

12. Mechanical Energy
When you kick a football, you give mechanical energy to the football to make it move.

13. Mechanical Energy
When you throw a bowling ball, you give it mechanical energy to make it roll.

14. Mechanical energy is made up of two energies:
Kinetic energy
Potential energy

15. Mechanical Energy Formula
ME = KE + PE

16. Kinetic Energy Kinetic energy is the energy due to motion.
Depends on both mass and velocity.
The more mass an object has, the more kinetic energy.
The faster an object moves, the more kinetic energy.

17. Kinetic Energy
This bird has kinetic energy because it has mass and velocity.

18. Kinetic Energy

19. Kinetic Energy: Problem Solving

20. Kinetic Energy: Problem Solving

21. Potential Energy Potential Energy is due to an object’s position.
Sometimes called “stored energy”
The object now has the “potential” to do work on an object (it’s just not doing it now).
Symbol: PE
There are two kinds of potential energy:
Gravitational Potential Energy
Elastic Potential Energy

22. Gravitational Potential Energy
PEg depends on height and mass.
The greater the height, the greater the PEg.
The greater the mass, the greater the PEg.

23. Gravitational Potential Energy
A waterfall, a suspension bridge, and a falling snowflake all have gravitational potential energy because they are above the ground.

24. Gravitational Potential Energy
PEg = mgh
Where:
m = mass (should be in kilograms)
g = acceleration due to gravity = 10 m/s2
h = height (usually above the ground or floor) (should be in meters)
PEg is usually measured in Joules
(1 kgm2/s2 = 1 Nm = 1 Joule)

25. Gravitational PE: Alternate Formula
PEg = m g h
Notice that the formula has mg… Oh… what is mg??? mg = weight!
Alternate formula:
PEg = weight  height
Remember: weight is measured in Newtons, mass is measured in kg

26. Gravitational Potential Energy
If you stand on a 3 m diving board, you have 3 times the PEg you had on a 1 m diving board.

27. Elastic Potential Energy
PEelastic depends on how much an object is being stretched or compressed.

28. Potential Energy: Problem Solving

29. Potential Energy: Problem Solving