Transcript Unit f Chapter 3 FORMS OF ENERGY

 What
is energy?
 Energy – is the ability to cause changes in
matter.
 Changing states of matter is a good example.
Solid
Activity
Liquid
Gas
 Kinetic
energy –
the energy of
motion.
 Any matter in
motion has kinetic
energy.
 Look at this ping
pong ball, when
does it have
kinetic energy?
Potential energy – is
the energy an object
has because of where
it or because of its
position.
 Lets look again at the
ping pong ball.
Where does the ball
have potential
energy?

 The
change in energy from potential to
kinetic is called the Transformation of
Energy.
 Even though energy can transform from one
form to another, it cannot be created or
destroyed. This is called the: Law of
Conservation of Energy.

Types of Kinetic Energy:
Mechanical – energy moving objects have.
Thermal – movement of molecules of matter.
 Electric – movement of electrons
 Light – pictures that move to your eyes in waves.
 Sound – vibrations heard through the ear that also
move in waves.



Types of Potential Energy:
Elastic – energy found in compressed springs or rubber
bands.
 Gravitational – energy an object has in an elevated
position
 Chemical – stored energy in the food we eat.


Is changed into thermal or mechanical energy by our
bodies for energy and heat.
What is energy?
What is kinetic energy?
You use mechanical energy to walk around.
What form did this energy have before your
body changed it to mechanical energy?
If you toss a ball in the air, at what point does
it have the most potential energy?
What law states that energy can’t be created
or destroyed?
1.
2.
3.
4.
5.
a)
b)
c)
d)
The
The
The
The
law
law
law
law
of
of
of
of
mechanical energy
conservation of energy
kinetic energy
potential energy
 How
has ever
received a shock
when touching a
metal object?
 How many of your
have every
shocked someone
or been shocked
yourself?
 What causes the
shock to occur?

Electric energy is
produced by the
movement of
electrons.


Electricity is all around
us; in lights televisions
and the radio.
Within an atom are
electrons with a
negative charge.
Protons have a
positive charge. They
attract to each other.
 When
an object
gains or loses
electrons it has an
electric charge.


If the object gains
electrons is has a
negative charge.
If it loses electrons
it has a positive
charge.

Electric force is the
attraction or repulsion
of charges.

Like charges repel
 Unlike charges attract.

Electric force depends
on distance. The
charge will be greater
the closer two objects
are.



Charged objects have
potential electric
energy.

AKA static electricity
The electrons aren’t
moving until the
charged objects are
close enough to each
other that the potential
energy is changed into
kinetic.
Electrons flow from
negatively charged
objects to positively
charged objects.





Electric current – is the
flow of electrons.
Electric Circuits – is any
path along which
electrons can flow.
Conductor – material
that conducts electrons
easily.
Insulator – is a material
that doesn’t carry
electrons easily.
Resistor – Don’t stop the
flow of electrons
completely, but resist
the flow in some way.

Examples of Conductors


Metals
Examples of Insulators
Rubber
 Plastic
 Glass
 Air


Examples of Resistors

Filament (light bulbs)
 Electromagnet
–a
current carrying
wire is wrapped
around a magnet.
 Only magnetized
when electricity is
flowing through it.
How do like electric charges react to each other?
Why are insulators placed around electric
conductors?
What are resistors, and why are they important?
Are the lights in your school connected in a series
circuits or parallel circuit? Explain.
1.
2.
3.
4.
•
Clue: Does on burned out light, turn off every other
light?
A coil that is magnetized only when an electric
current flows through it is ?
5.
a.
b.
c.
d.
Battery
Generator
Conductor
Electromagnet
 Light

Energy
Light rays are a
form of energy that
can travel through
empty space or
through some kinds
of matter.
 Reflection
vs.
Refraction


Reflection – other
colors bounce off
objects.
Refraction – the
bending of light
rays.
 Convex




Is thicker in the
middle than at the
edges.
When light passes
through the light
rays bend toward
each other.
Magnifying glass is
an example.
Farsighted.
 Concave





This lens is thicker
around the edges than
the middle.
When light rays pass
through this lens they
bend away from each
other.
They make objects
nearer seem smaller
Cameras are an
example.
Nearsighted




Light energy is also
called electromagnetic
waves.
Visible light waves are
those we can see, but
they are just a small
part of the
electromagnets waves
produced.
Other examples: Radio
waves, x-rays,
microwaves.
Does not need matter
to move through; it can
move through space.

Visible light waves are
different color
wavelengths.

The human eye senses
different wavelengths as
different colors of light.

Long wavelengths appear
red, were as short
wavelengths appear
violet. Between red and
violet are all the colors of
the rainbow.
 ROYGBV
is an
acronym to help
you remember
visible wavelength
colors.
R – red
O – orange
Y – yellow
G – green
B – blue
V - violet




Lens – light passes through
the clear lens.
Iris – is the colored part of
the eye. It narrows in bright
light and narrows in
darkness.
Cornea – light enters through
the cornea and bends light
rays
Retina – an upside-down
image falls here where cells
change light energy to
electric and chemical energy
in the form of nerve
impulses. This is were the
blind spot in the eye is
located, because there are
no photoreceptors were the
optic nerve is located.
What is refraction?
What type of lens would you use to magnify
your view of a butterfly?
If a bright explosion took place in space,
would it be seen on Earth?
Which part of the eye has cells that change
light energy into nerve impulses?
1.
2.
3.
4.
a)
b)
c)
d)
The iris
The blind spot
The lens
The retina
 Thermal
energy – is the kinetic energy of
molecules.
 Temperature – is the average kinetic energy
of all the molecules in an object. The higher
the average kinetic energy, the faster the
molecules, the higher the temperature.
 Heat – is the transfer of thermal energy from
one substance to another.
It always flows in the same direction.
Warmer
Colder

 Conduction
– is the
DIRECT transfer of
thermal energy
between objects
that touch.
 Conductors and
Insulators are
important when
using conduction.
 Convection
– is
thermal energy
transfer as the
result of the
mixing of a liquid
and a gas.
 Radiation
– is the
transfer of thermal
energy by
electromagnetic
waves.
 Only radiation can
transfer thermal
energy through
space. An example
is the heat you feel
from the sun.
3
1.
2.
3.
ways Thermal Energy can be transferred
Conduction
Convection
Radiation
 Chemical
energy – energy that is stored as a
form of potential energy.
 Chemical energy can be transferred into
kinetic energy.
 Our body uses this chemical energy to carry
out daily activities and maintain our body
temperature.
What is convection?
What type of heat transfer takes place when you
burn your hand on a stove?
Two atoms absorb thermal energy when joining
together to form a molecule. What happens to the
thermal energy?
Suppose you drop an ice cube into a warm drink,
and it melts. How is thermal energy transferred?
Which form of energy transfer allow you to feel the
warmth of the sun on your face?
1.
2.
3.
4.
5.
a.
b.
c.
d.
Radiation
Conduction
Convection
Chemical energy