Energy and the two types of energy

1. ENERG
Y
Grade 8 Science

2. 3. Explain how kinetic energy differ
from potential energy;
4. Compute problems involving
potential and kinetic energy.
1. Define energy;
2. Identify activities/things that
possesses kinetic energy or
potential energy;
OBJECTIVES

3. ENERGY
What is it?

4. ENERGY
WHAT is ENERGY?
• It comes from the Greek
word energeia meaning
“in or at work.”
• Energy is the ability
of any matter to do or
perform work.
• It is the capacity to
do work.

5. ENERGY

6. MESSAGE RELAY
First Game
ENERGY

7. Two Main Types of Energy
KINETIC ENERGY
POTENTIAL ENERGY
and
ENERGY

8. ENERGY
GROUP QUIZ
Second Game

9. Time is Up!

10. A mouse running away from cat.
KINETIC
ENERGY
1

11. A boulder sitting on top of Mountain
POTENTIAL ENERGY
2

12. 3 An eagle resting on its nest on the top
of the tree
POTENTIAL ENERGY

13. 4 A car driving around the rotunda
KINETIC ENERGY

14. 5 A ball rolling downhill
KINETIC ENERGY

15. 6 A stretched bow
POTENTIAL ENERGY

16. 7 Sailing boat
KINETIC ENERGY

17. 8 Books in a shelf
POTENTIAL ENERGY

18. 9 Stretched Rubber band
POTENTIAL ENERGY

19. How does kinetic energy differ from
potential energy?
Category 4 3 2 1
Teamwork All members shared their
ideas and participated in
the activity
Most of the
members shared
their ideas and
participated in the
activity
Only few of the
members shared
their ideas and
participated in the
activity
Members do not
seem to care
about the activity
Content Shows full understanding
of the topic
Shows good
understanding of
the topic
Shows good
understanding of
parts of the topic
Does not seem
to understand
the topic very
well
Delivery Speaks clearly and
distinctly (96-100%) all
the time
Speaks clearly and
distinctly (90-95%)
all the time
Speaks clearly
and distinctly (85-
89%) all the time
Often mumbles
or cannot be
understood
Posture and
Eye Contact
Stands up straight, looks
relaxed and confident.
Establishes eye contact
with everyone in the
room during the
presentation
Stands up straight
and establishes eye
contact with
everyone in the
room during the
presentation
Sometimes stand
up straight and
establishes eye
contact
Slouches and/or
does not look at
people during
presentation
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End

20. Two Main Types of Energy
1. Kinetic Energy
- is the energy in motion

21. KINETIC
ENERGY
• Kinetic energy depends on both mass
and velocity.
• It can be obtained through this equation:
Where:
KE = Kinetic Energy
m = mass
v = velocity
2
2
1
mv
KE 

22. A 9.0 kg bowling ball slides on the lane at a
velocity of 3.0 m/s. What is ball’s Kinetic
Energy?
KINETIC
ENERGY

23. KINETIC
ENERGY
Given:
Required:
Formula:
Solution:
m=9.0 kg
v=3.0 m/s
KE?
2
2
1
mv
KE 
KE = ½ (9.0kg)(3.0m/s) 2
= ½ (9.0kg)(9.0m 2/s 2)
= ½ (81 kg m 2/s 2)
= 40.5 Joules
KE = 41 J
A 9.0 kg bowling ball slides on the lane at a velocity of 3.0 m/s.
What is ball’s Kinetic Energy?

24. KINETIC
ENERGY
A 9.0 kg bowling ball slides on the lane at a velocity of 3.0 m/s.
What is ball’s Kinetic Energy?
Assuming that the bowling has different mass and velocities, What would
be its Kinetic Energy?
Group 1
Mass = 6.0 kg
Velocity = 2.0 m/s
Group 2
Mass = 12 kg
Velocity = 4.5 m/s
Group 3
Mass = 3.6 kg
Velocity = 1.8 m/s
Group 4
Mass = 15.4 kg
Velocity = 6 m/s
2
2
1
mv
KE 

25. COMPUTATIONS
Third Game
KINETIC
ENERGY

26. What is your Kinetic energy if you have the
velocity of 2.5 m/s as you run from the library
to the room provided that your mass is 40 kg?
KINETIC
ENERGY

27. 500 kg motorcycle is traveling with a velocity
of 1.3 m/s, find its KE.
KINETIC
ENERGY

28. Two Main Types of Energy
2. Potential Energy
- is a stored energy
 It is energy possessed by an object due
to their compositions & positions

29. POTENTIAL
ENERGY
Water behind the dam

30. POTENTIAL
ENERGY
Potential Energy can be:
Gravitational Potential Energy
Elastic Potential Energy
Chemical Potential Energy
Energy which is in position to object’s position
relative to a certain height
Energy that is stored in a elastic materials
(Stretched/compressed)
Energy that is inherent in all substances like
petrol, wood, and plants

31. POTENTIAL
ENERGY
• The relationship of height and mass and
influence of gravity to PE can be expressed in
this equation:
PE = mgh
Where:
PE = Potential Energy
m = mass
g = gravitational acceleration (9.8 m/s2)
h = height

32. POTENTIAL
ENERGY
What is the potential Energy (PE) of a 8 kg object
raised to a height of 16 m.
Given:
Required:
Formula:
Solution:
m=8kg; h=16m
PE?
PE = (8kg) (9.8 m/s2) (16m)
= 1,254.4 Joules
PE = mgh

33. POTENTIAL
ENERGY
What is the potential Energy (PE) of a 8 kg object
raised to a height of 16 m.
Assuming that the object has different mass and height, What would be
its Kinetic Energy?
Group 1
Mass = 6.0 kg
Height = 2.0 m
Group 2
Mass = 12 kg
Height = 4.5 m
Group 3
Mass = 3.6 kg
Height = 1.8 m
Group 4
Mass = 15.4 kg
Height = 6 m
PE = mgh

34. POTENTIAL
ENERGY
COMPUTATIONS
Fourth Game

35. Jona lifts her 0.30 kg book from the flor to her desk
which is 0.60 m high. Find the Gravitational
Potential energy gained of the book.
POTENTIAL
ENERGY

36. Jill brings a 5 kg pail of water on a hill and leaves it
on the top of the hill, which is 5 m above the
ground. What is the PE does the pail have?
POTENTIAL
ENERGY

37. 3. Explain how kinetic energy differ
from potential energy;
4. Compute problems involving
potential and kinetic energy.
1. Define energy;
2. Identify activities/things that
possesses kinetic energy or
potential energy;
OBJECTIVES

38. QUIZ
Definition of Terms. Define
the following
1.Energy
2.Kinetic Energy
3.Potential energy

39. QUIZ
Identification. Identify the following
as Kinetic or Potential
1. Running car
2. Sleeping cat
3. Flying airplaine
4. Book at the table
5. Stretched rubber band

40. QUIZ
Essay
1. A rock and a feather are dropped
from the same height. Which has
more Kinetic energy? Rock or a
feather? Explain your answer.
2. How Kinetic energy differ from
potential energy?

41. QUIZ
Problem Solving. Provide what is given, required,
formula & solution and conclusion.
1.Suppose you pedal a 25 kg bicycle
at 1.5 m/s. Find the kinetic energy of
the bicycle.
1.Calculate the potential energy does
400 kg of water in Maria Christina
Falls has at height of 100m?

42. 1. What is the height of the ladder from
the ground if you climb at it with
your mass of 45 kg and you obtain
potential energy of 4,410 Joules?
2. The dog is running with the kinetic
energy of 2,345 Joules. Assuming
that the dog has a velocity of 0.85
m/s2, what is the mass of the dog?
ASSIGNMENT

43. WORK
Grade 8 Science

44. 3. Explain how work is related to
energy;
4. Compute work done by a constant
force.
1. Define work scientifically;
2. Identify situations in which work
is done and in which no work is
done;
OBJECTIVES

45. WORK
What is it?

46. • It is scientifically defined as the
product of the force exerted on an
object and the distance the object
moved to the direction of the force.
WORK
W=Fd
Where: W=work
F=Force
d=distance/displacement
work =
Amount of force applied
In the direction of motion
Distance over which the
force is applied
x

47. WORK
A girl pushing a chair
Is there any work done?
YES,
there is work done.

48. WORK
Is there any work done?
No,
there is no work done.
A boy pushing a wall

49. WORK
Is there any work done?
No,
there is no work done.
A waiter carrying a tray

50. Work is done on an object when the force applied to it
covers a distance in the direction of the applied force.
Work is done
No Work is done
No Work is done
WORK

51. WORK
Is there work done?

52. Calculating a Work
WORK
Work is done when the force (F) applied to the object causes the object to
have a displacement (d) in the same direction as the force applied.
W=Fd Where: W=work
F=Force
d=distance/displacement

53. WORK
Unit for Work
James Prescott Joule
One (1) Joule is equal to the work
done or energy expended in
applying a force of one Newton
through a distance of one meter.

54. WORK
Suppose a woman is pushing a grocery cart with a 500 Newton
force along the 7 meters aisle, how much work is done in
pushing the cart from one end of the aisle to the other?
Given:
Required:
Formula:
Solution:
F = 500 N
d = 7 m
W = ?
W = Fd
W = 500 N (7m)
W = 500 Nm
W = 3500 J

55. WORK
Suppose a woman is pushing a grocery cart with a 500 Newton force
along the 7 meters aisle, how much work is done in pushing the cart
from one end of the aisle to the other?
Supposing that a woman is having different amount of forces applied in
pushing the grocery cart with distinct distances. How much is the work?
Group 1
Fore = 350 N
Distance = 6 m
Group 2
Force = 700 N
Distance = 9.2 m
Group 3
Force = 156 N
Distance = 2.6 m
Group 4
Force = 875 N
Distance = 14 m
W=Fd