1. Physical Science: Chapter 13
Section 3: Energy

2. Physical Science: Chapter 13 Section 3: Energy
The ability to do WORK
Whenever Work is done, energy MUST
a). Be transferred between objects OR
b). transformed into another form of
energy.

3. Physical Science: Chapter 13 Section 3: Energy
The amount of energy used can be found by calculating the amount of Work done.
Work = Force x distance

4. Physical Science: Chapter 13 Section 3: Energy
Because energy is the ability to do Work, Work and Energy are measured in the same units, Joules.

5. Physical Science: Chapter 13 Section 3: Energy
There are two broad categories of energy:
1. potential energy
2. kinetic energy

6. Physical Science: Chapter 13 Section 3: Energy
POTENTIAL ENERGY
Potential energy is the stored energy of a system.
It is also called the energy of position, because it can result from the relative position of objects in a system.

7. Physical Science: Chapter 13 Section 3: Energy
POTENTIAL ENERGY
There are multiple kinds of potential energy:
Gravitational potential energy
Elastic potential energy
Chemical potential energy
Electric potential energy

8. Physical Science: Chapter 13 Section 3: Energy
POTENTIAL ENERGY
Gravitational potential energy
is created by
positioning an
object above
the surface of
the Earth.

9. Physical Science: Chapter 13 Section 3: Energy
GRAVITATIONAL POTENTIAL ENERGY
● Depends on: the mass of the object, the acceleration due to gravity and the height above the surface of the Earth.
G.P.E. = m x g x h
Units:
kg * m/s2 * m = kg*m2/s2 = joules

10. Physical Science: Chapter 13 Section 3: Energy
GRAVITATIONAL POTENTIAl ENERGY
● Since the (m x g) = weight,
G.P.E. = w x h

11. Physical Science: Chapter 13 Section 3: Energy
GPE: Practice Problems
1). What is the GPE of a 65kg rock climber, 35m up the face of a cliff? (g = 9.8m/s2)
2). If a rock with a weight of 25N has a GPE of 175J, how high up is the rock?

12. Physical Science: Chapter 13 Section 3: Energy
GPE: Practice Problems
1). What is the GPE of a 65kg rock
climber, 35m up the face of a cliff?
G.P.E. = m x g x h
GPE =(65kg)(9.8m/s2)(35m)
GPE = 22,295J

13. Physical Science: Chapter 13 Section 3: Energy
GPE: Practice Problems
2). If a rock with a weight
of 25N has a GPE of
175J, how high up is
the rock?

14. Physical Science: Chapter 13 Section 3: Energy
GPE: Practice Problems
2). If a rock with a weight of 25N has a
GPE of 175J, how high up is the rock?
G.P.E. = weight x h
175J=(25N)(h)
h =175J/25N = 7m

15. Physical Science: Chapter 13 Section 3: Energy
ELASTIC POTENTIAL ENERGY
● Depends on
the strength of the elastic band, spring or other bent object
the distance that the band, spring or object is bent.

16. Physical Science: Chapter 13 Section 3: Energy
ELASTIC POTENTIAL ENERGY
● Depends on the strength of the elastic band, for things like
slingshots.

17. Physical Science: Chapter 13 Section 3: Energy
ELASTIC POTENTIAL ENERGY
● Depends on the
strength of
the bent bow,
for archery.

18. Physical Science: Chapter 13 Section 3: Energy
ELASTIC POTENTIAL ENERGY
● Depends on the strength of
springs, when
stretched out
or compressed.

19. Physical Science: Chapter 13 Section 3: Energy
ELASTIC POTENTIAL ENERGY
● ALSO depends on how FAR
the band,
bow, or
spring is
pulled.

20. Physical Science: Chapter 13 Section 3: Energy
CHEMICAL POTENTIAL ENERGY
● Is a type of potential energy stored in
the bonds
in chemical
compounds.

21. Chemical Potential Energy

22. Physical Science: Chapter 13 Section 3: Energy
CHEMICAL POTENTIAL ENERGY
● Nuclear energy is released
by changes in
the structure
of atoms’
nuclei.

24. Physical Science: Chapter 13 Section 3: Energy
ELECTRIC POTENTIAL ENERGY
● Is a type of potential energy stored in
electric
fields

25. Physical Science: Chapter 13 Section 3: Energy
Mini-Quiz #3
1). What is the definition of energy?
2). What UNITS is energy measured in?
3). What are the TWO categories of energy?
4). Name FOUR types of potential energy?

26. Physical Science: Chapter 13 Section 3: Energy
Mini-Quiz #3 5). What is the formula for GPE? 6). What is the GPE of a 100kg person, 100m above ground? 7). If a 900N person has a GPE of 27,000J, how high up are they? 8). What TWO things does elastic potential energy depend on?

27. Physical Science: Chapter 13 Section 3: Energy
Team Mini-Quiz #1
1). What is the definition of energy?
The ability to do Work.
2). What UNITS is energy measured in?
Joules
3). What are the TWO categories of energy?
Potential and kinetic

28. Physical Science: Chapter 13 Section 3: Energy
Team Mini-Quiz #1
4). Name FOUR types of potential energy?
Gravitational, elastic,
chemical & electric
5). What is the formula for GPE?
GPE = m x g x h

29. Physical Science: Chapter 13 Section 3: Energy
Team Mini-Quiz #1
6). What is the GPE of a 100kg person, 100m
above ground?
GPE = (100kg)(9.8m/s2)(100m)
GPE = 980,000J
7). If a 900N person has a GPE of 27,000J, how
high up are they?
27,000J = 900N* h
h = 27,000J/900N = 30m

30. Physical Science: Chapter 13 Section 3: Energy
Team Mini-Quiz #1
8). What TWO things does elastic potential
energy depend on?
The strength of the band, bow or spring and the distance the band, bow or spring is pulled (or pushed).

31. Physical Science: Chapter 13 Section 3: Energy
KINETIC ENERGY
Kinetic energy is the energy possessed by moving objects.

32. Kinetic Energy
Kinetic Energy is dependent on the mass and the velocity of the object. The formula is:
KE = ½ mv2
Notice that the Kinetic Energy (KE) is affected by both mass and velocity (speed). However, the speed (velocity) makes a greater difference because it is squared in the equation.
Units are kg*m2/s2 which is equal to a Joule.

33. Practice Problems Potential Energy page 446- #1-3 Kinetic Energy

34. Summary