Download What is Electrical Energy?

Soda Time
T. Trimpe 2008 http://sciencespot.net/
•Find the 7 differences between the two pictures.
•Source: http://2.bp.blogspot.com/_ft3_uLg4mmQ/RoBui7mA7LI/AAAAAAAAACY/j7ya0tyPzds/s1600-h/Puzzle.jpg
•The answers are …
•Source: http://2.bp.blogspot.com/_ft3_uLg4mmQ/RoBui7mA7LI/AAAAAAAAACY/j7ya0tyPzds/s1600-h/Puzzle.jpg
Let’s Review This Unit So Far…
What is Force Again?
Force is a push or a pull on an object
Unbalanced Forces Vs.
Balanced Forces
• Unbalanced forces • Balanced forces are
can cause an
object to move,
stop moving, or
change direction.
the forces in equal
and opposite
directions
Forces Change
Motion!
Newton’s First Law of Motion
Momentum
Newton’s Second Law
• Defines force as a change in momentum with a change in time
∆(mv)
F=
∆t
• In order to change one’s momentum, an impulse must be applied
– Impulse is a force exerted on an object over a period of time
• Since mass is essentially constant for an object, Newton’s 2nd Law
becomes:
∆(v)
F=m
∆t
• The change in velocity divided by the change in time (
definition of acceleration, a
∆(v)
)
∆t
is the
Therefore:
Force and Mass
Determine
Acceleration!
F = ma
Newton’s Third law
• If an object exerts a force
on another object, the
second object, exerts an
equal force in the opposite
direction.
Newton’s Third Law and
Momentum
• As stated in Newton’s 3rd Law, the
forces acting between two objects in a
interaction (collision) are equal in
magnitude and opposite in direction
F1 = −F2
• The time the force acts upon object 1
is equal to the time that the force acts
upon object 2
t1 = t 2
Newton’s Third Law and
Momentum
• It then follows that the impulses
experienced by these two objects are also
equal in magnitude and opposite in
direction
F1 × t1 = −F2 × t 2
• But the impulse experienced by an object is
equal to the change in momentum of that
object
– So, each object experiences equal and
opposite momentum changes!
MOMENTUM IS CONSERVED IN A COLLISION!
This Idea is Called the Law of
Conservation of Momentum
• The total momentum of
objects that interact does not
change
• The momentum of a bowling
ball is equal to the
momentum of the pin it hits
COLLISIONS
This Directly Relates to the
Law of Conservation of Energy!
• Like the Law of Conservation of Momentum, the
Law of Conservation of Energy is a fundamental
principle in the physical world
• The law states that energy cannot be created or
destroyed
– It may be transformed from one form into another,
but the total amount of energy never changes!
• If energy seems to disappear, then scientists look
for it – leading to many important discoveries
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.
Nature of Energy
• You use energy when you:
– hit a softball.
– lift your book bag.
– compress a spring.
• The combination of energy
and matter make up the
universe!
Energy
• Energy exists in many forms.
• Energy can be moved from one object
to another.
• Energy can be changed from one form
to another.
• Energy cannot be created or
destroyed.
What is Always Present
But Never Visible?
•ENERGY
Although energy isn’t visible,
you can detect evidence of energy.
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
• Work is done when a force is
exerted over a distance
Work
• Again, work is equal to the force that is
exerted times the distance over which it is
exerted
W=Fxd
• The unit of work combines the unit of force
(N) with the unit of distance (m)
– Newton-meter (N-m) aka the Joule (J)
Nature of Energy
• Because of the direct connection between
energy and work, energy is measured in the
same unit as work: joules (J)
• If an object or organism does work, the object
or organism uses energy
• In addition to using energy to do work, objects
can gain energy because work is being done on
them
You carry a 20 kg suitcase upstairs, a distance of 4m
with an acceleration of 10 m/s2. How much work did
you do?
W=Fxd
• We must first find the force!
F = ma
= (20 kg) (10m/s2) = 200 N
• Now, we can solve for work
W=Fxd
= (200 N) (4m)
= 800 J
Energy is in Either of Two States:
Potential
Kinetic
• energy of position or • energy of motion, the
energy in storage
form capable of doing
work
– Water behind a dam
– Hammer over head
– Food on the plate
– Flowing water
– A falling hammer
– Electrons regenerating
ATP in a biological cell
Potential Energy
The energy in matter due to its position or the
arrangement of its parts
Kinetic Energy
Energy of a moving object
Kinetic Energy
• Kinetic energy depends on both mass and
velocity
• Equation:
KE = 1/2 m v2
• The faster an object moves, the more kinetic
energy it has
• The greater the mass of a moving object, the
more kinetic energy it has
• The work done on an object by a net force equals
the change in kinetic energy of the object!
W=∆KE = KEf -KEi
KE = 1/2 m v2
W=∆KE = KEf -KEi
• What was your
velocity going up the
stairs if you and the
suitcase have a mass
of 60Kg?
• W= 800J
• M= 60 Kg
• 800J= ½ (60Kg) v2
• 26.7= v2
• V= 5.2 m/s
Six Forms of Energy
•Mechanical
•Heat/Thermal
•Chemical
•Nuclear
•Electrical
•Light/Radiant
What is Mechanical Energy?
• Energy that moves objects
from place to place
– Due to an object’s motion
OR position
• You use mechanical energy
when you kick a ball or turn
the pedals of a bicycle
• Other examples include
water flowing in a stream,
tires rolling down a road
and sound waves from your
iPod.
Examples of Mechanical Energy
What is Electromagnetic or Light
Energy?
o Also called radiant
energy
o Energy that can move
through empty space
Light (Radiant) Energy
• The sun and stars are
powerful sources of
radiant energy
• The light given off by
light bulbs and campfires
are also forms of radiant
energy
• Also includes energy
from gamma rays,
xrays, ultraviolet rays,
visible light, infrared
rays, microwave and
radio bands
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
Electrical Energy
• It can be generated at a
power plant or inside a
battery and can power
everything from remotecontrolled cars to
refrigerators
• Lightning and static
electricity are also forms of
electrical energy
What is Chemical Energy?
• Energy released by a
chemical reaction
• The food you eat contains
chemical energy that is
released when you digest
your meal
• Wood, coal, gasoline, and
natural gas are fuels that
contain chemical energy
Examples of Chemical Energy
What is Thermal Energy?
o
Also called heat energy
• Energy created by the motion of
atoms and molecules that
occurs within an object
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
Nuclear Energy
• Energy contained in the
nucleus of an atom
• Nuclear energy is released
when nuclei are split apart
into several pieces, or
when they are combined to
form a single, larger
nucleus
Nuclear Energy
•The sun’s energy is
produced from a
nuclear fusion
reaction in which
hydrogen nuclei
fuse to form helium
nuclei.
Energy Conversion
• All forms of energy can be converted into
other forms of energy!
QUIZ TIME!
What type of energy
cooks food in a
microwave oven?
ELECTROMAGNETIC
ENERGY
What type of energy is
the spinning plate inside
of a microwave oven?
MECHANICAL ENERGY
QUIZ TIME!
Electrical energy is
transported to your house
through power lines.
When you plug an electric fan
to a power outlet, electrical
energy is transform into what
type of energy?
MECHANICAL ENERGY
QUIZ TIME!
What energy transformation
occurs when an electric lamp is
turned on?
ELECTRICAL ENERGY

ELECTROMAGNETIC ENERGY
What types of energy are shown below?
Mechanical and Thermal Energy
(Don’t forget friction)
What type of energy is shown below?
Chemical Energy
What types of energy are shown below?
Electrical, Mechanical and
Electromagnetic Energy
What type of energy is shown below?
Chemical Energy (yummy)
What type of energy is shown below?
Thermal Energy
Inertia Video