Energy can exist in multiple forms and transforms between potential and kinetic. The document discusses various types of energy like gravitational potential energy, elastic potential energy, chemical potential energy, and kinetic energy. It also covers the law of conservation of energy, which states that energy cannot be created or destroyed, only transformed from one form to another. Examples are provided to demonstrate calculating gravitational potential energy, kinetic energy, and using equations like KE=1/2mv^2 and GPE=mgh to solve problems involving energy transformations.

1. energy

2. • “the ability to do work”
• The combination of energy and matter
make up the universe:
– Matter is substance, and energy is the
mover of substance.
What is energy?

3. The Law of Conservation of
Energy
• Energy cannot be created or destroyed; it
may be transformed from one form into
another, but the total amount of energy
never changes.

4. Energy is
nature’s way of keeping score.
We sense energy only
when the score
changes,
either a transformation
from one form of
energy to another,
or a transfer of energy
from one point to
another.

5. How is all energy divided?
Potential
Energy
Kinetic
Energy
All Energy
Gravitation
Potential
Energy
Elastic
Potential
Energy
Chemical
Potential
Energy

6. Potential Kinetic
• energy of position
or energy in
storage.
– Water behind a dam
– Hammer over head
– Food on the plate
• energy of motion,
the form capable of
doing work
– Flowing water
– A falling hammer
– Electrons regenerating
ATP in a bio’l cell

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

8. GPE = mgh
• m = mass (kg)
• h = height (m)
• g = acceleration due to
gravity (10 m/s2)

9. Example .1
• How much gravitational potential
energy is lost by a 5Kg object to
kinetic energy due a decrease in
height of 4.5 m
• GPE = mgh
• GPE = (5Kg) x(10 m/s2)x (4.5 m)
• GPE = 225 J

10. 10.3 Potential Energy
• A cart with a mass of 102 kg is
pushed up a ramp.
• The top of the ramp is 4 meters
higher than the bottom.
• How much potential energy is
gained by the cart?
• If an average student can do 50
joules of work each second,
how much time does it take to
get up the ramp?

11. 1. An object has a mass of 1500g. What is
its gravitational potential energy
1. 4m above the ground
2. 650cm above the ground
2. How high should a car of mass = 15
tonnes be to have a GPE of 2.0x106J?

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

13. OTHER FORMS OF POTENTIAL ENERGY
1. Elastic Potential Energy
o Potential energy due compression or
expansion of an elastic object.
Notice the ball compressing
and expanding

14. 2. Chemical Potential Energy
o Potential energy
stored within the
chemical bonds of
an object

15. •
3. Mechanical energy is the energy possessed by
an object due to its motion or its position.
4. Radiant energy includes light, microwaves, radio
waves, x-rays, and other forms of
electromagnetic waves. It is also called
electromagnetic energy.
5. Nuclear energy is released when heavy atoms in
matter are split up or light atoms are put
together.
6. The electrical energy we use is derived from
other sources of energy.

16. What is Electrical Energy?
o Energy caused by
the movement of
electrons
o Easily transported
through power lines
and converted into
other forms of
energy

17. What is Thermal Energy?
o Heat energy
o The heat energy of an
object determines how
active its atoms are.
A hot object is one whose
atoms and molecules are
excited and show rapid
movement.
A cooler object's molecules
and atoms will show less
movement.

18. What is the source of our
energy?
• The source of
practically all
our energy is
the Sun.

20. Kinetic Energy
• Energy of motion is called kinetic energy.
• The kinetic energy of a moving object
depends on two things: mass and speed.
• Kinetic energy is proportional to mass.

21. Kinetic Energy
K.E = 1
mv2
2
Speed (m/s)
Mass (kg)
Kinetic Energy
(Joules)

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

23. Law of Conservation of Energy
• As energy takes different forms and
changes things by doing work, nature
keeps perfect track of the total.
• No new energy is created and no existing
energy is destroyed.

24. 5.3 Energy Transformations
Key Question:
Where did the energy go?

25. A 5kg block falls from a height of 12m.
Calculate:
a. The G.P.E that the block had before the
fall.
b. The K.E in the block just before hitting the
ground.
c. The velocity with which the block hits the
ground.
Exercise
Q.1.

26. Q.2.
A car with a mass of 1,300 kg
is going straight ahead at a
speed of 30 m/sec (67
mph).
The brakes can supply a force
of 9,500 N.
Calculate:
a) The kinetic energy
of the car.
b) The distance it takes
to stop.

27. PREP
A ball has a mass of 0.75kg. Dropped from a cliff
top, the ball hits the sea at a speed of 10m/s.
a. What is the kinetic energy of the ball as it is
about to hit the sea?
b. What was the ball’s gravitational potential
energy before it was dropped?
c. From what height was the ball dropped?
d. A stone of mass 1kg also hits the sea at 10m/s.
repeat stages a, b, and c above to find the
height from which the stone was dropped.

28. Energy and Conservation of Energy
Key Question:
How is motion on a
track related to
energy?

29. Application: Hydroelectric Power

30. Thank you!