1. Physical Science Unit 3-5
Energy!!
Physical Science
Unit 3-5

2. What is Energy? The ability to cause change
When does something have energy?
It has the ability to change itself or its environment

3. 2 Categories of Energy Kinetic Energy Potential Energy
IS changing an object or its surroundings
The energy in a moving object
Potential Energy
COULD BE or has the POTENTIAL to change an object or its surroundings
Energy stored within an object

4. Types of Energy Kinetic Energy Potential Energy Electromagnetic Energy
Motion- large objects
Thermal or Heat energy- tiny molecule motion
Potential Energy
Elastic- stretch
Chemical- bonds, fuel
Nuclear- nucleus
Electrical- charge
Gravitational- height
Electromagnetic Energy
Energy carried by
invisible waves

5. Kinetic Energy The energy a moving object has because of its motion
Depends on mass and speed!

6. Thermal or Heat Energy Kinetic energy in tiny molecules Hotter objects
Molecules vibrating
faster
Colder objects
slower

7. Kinetic Energy Equation
Kinetic Energy = 1 mass x (speed)2 2
KE = 1 mv2
KE = Joules (J)
Kinetic Energy

8. Example!
Diego is jogging. His mass is 60 kg and he is moving at 3 m/s. What is his KE?
m = 60 kg
v = 3 m/s
KE = 1mv2 2
KE = 1/2 (60)(3 2)
KE = 270 J

9. Potential Energy
Stored energy due to position
Potential Energy

10. Elastic Potential Energy
Energy stored by something that can stretch or compress
Example = Rubberband or Spring

11. Chemical Potential Energy
Energy stored in chemical bonds
Example = food- fuel

12. FUEL

13. Electrical Potential Energy
Stored energy due to an electric charge
Example = rubbing socks on carpet, lightning from clouds to ground

14. Nuclear Potential Energy
Energy stored in the nuclei of atoms
Energy holds nucleus together
Fusion
Put atoms together (sun)
Fission
Break atoms apart (atom bomb)

15. Gravitational Potential Energy
Energy stored by an object due to its position over the Earth
Based on height and gravity
Anything that can fall!

17. Gravitational Potential Energy Equation
GPE = mass x gravity x height
GPE = mgh (Joules)
GPE = Fwh

18. Example!
What is the gravitational potential energy of a ceiling fan that has a mass of 7 kg and is 4 m above the ground?
m = 7 kg
h = 4 m
GPE = mgh
GPE = (7)(9.8)(4)
GPE = 274 J

19. Electromagnetic Energy
Electrical and Magnetic fields carry energy in invisible waves
Light
X-rays
UV rays
Microwaves
Radio waves

20. Changing Forms of Energy
Electrical to other forms

21. Changing Forms of Energy
Chemical to other forms

22. Conversions between KE & PE
Mechanical Energy - total amount of potential and kinetic energy in a system
Mechanical Energy = PE + KE

24. Law of Conservation of Energy
Energy cannot be created or destroyed
Total amount of energy in the universe does not change

25. Converting Mass into Energy
Nuclear fusion
Combining nuclei
Example - sun
Nuclear fission
Nuclei are broken apart
Both
Total amount of energy is conserved
Total amount of mass is conserved