1. Unit 6
Types of Energy
6.1

2. Nature of Energy Energy is all around you!
You can hear energy as sound.
You can see energy as light.
And you can feel it as wind.

3. Nature of Energy You use energy when you: hit a softball.
lift your book bag.
compress a spring.

4. Living organisms need energy for growth and movement.
Nature of Energy
Living organisms need energy for growth and movement.

5. Nature of Energy Energy is involved when: a bird flies.
a bomb explodes.
rain falls from the sky.
electricity flows in a wire.

6. Nature of Energy
What is energy that it can be involved in so many different activities?
Energy can be defined as the ability to do work or cause change.
If an object or organism does work the object or organism uses energy.

7. Work

8. TWO CATEGORIES OF ENERGY
KINETIC ENERGY
- energy of motion
2. POTENTIAL ENERGY
- energy that is stored in an object due to POSITION or CHEMICAL COMPOSITION

9. Kinetic Energy This is determined by an object’s MASS and SPEED
Faster object = Greater K.E.
Heavier object = Greater K.E.
*Speed has a GREATER EFFECT ON K.E. than mass does

10. Kinetic energy The formula for K.E. is: K.E. = (1/2)(mass)(velocity²)
*The unit for energy is the Joule (J)

11. What is Kinetic Energy?
K.E. = 1/2(mass x speed2)

12. KE = 1/2 m v2 .25 kg baseball 4 kg bowling ball at 50 m/s at 10 m/s
= .5 (.25kg) (50 m/s)2
= 312 J
4 kg bowling ball
at 10 m/s
= .5 (4kg) (10m/s)2
= 200 J

13. Practice
A 20-kg bicycle carrying a 50-kg girl is traveling at a speed of 8 m/s. What is the kinetic energy of the girl and bicycle?

14. Potential energy
Energy that is stored in an object as a result of its position, shape, or chemical composition.
3 Types

15. Gravitational Potential energy
Energy of an object that depends on its position relative to the Earth’s surface.
Direct relationship between G.P.E. and mass
Direct relationship between G.P.E. and height

16. GPE = mgh m = mass (kg) h = height (m) g = accel due to gravity
(9.8 m/s2)

17. Practice
A 70-kg boy is sitting 3 m from the ground in a tree. What is his gravitational potential energy?

18. What is Gravitational Potential Energy?
Potential energy due to an object’s position
P.E. = mass x
height x gravity
Don’t look down, Rover!
Good boy!

19. What is Potential Energy?
Energy that is stored and waiting to be used later

20. What is Elastic Potential Energy?
Potential energy due compression or expansion of an elastic object.
Notice the ball compressing
and expanding

21. Elastic potential energy
Formula
E.P.E. = (1/2)x spring constant(k) x distance compressed or stretched

22. What is Chemical Potential Energy?
Potential energy stored within the chemical bonds of an object