Download Chapter 3 Energy

Chapter 3
Energy
3.1 Energy exists in different forms.
Different forms of energy
have different uses.
***Just about everything you see
around you involves energy
Lamps use electrical energy
Plants use energy from the Sun
You are using food energy
Energy
Def - Energy is the ability to cause change.
What is energy?
Unlike matter, energy is a
property of an object.
Energy has no mass and no
volume.
Forms of Energy
1. Mechanical Energy – Energy
you use to move your body.
2. Sound Energy – Energy
produce by sound causes
particles to vibrate. People can
detect these vibrations.
3. Chemical Energy
Energy that is stored in the
chemical composition of matter is
chemical energy.
How much
chemical energy there is depends
on the type of atoms and how the
atoms are arranged.
Your energy comes from the chemical
energy stored in the foods you eat.
Thermal Energy –
Matter is made of atoms and
molecules that are always
moving.
The energy of the
motion in an object is the
object’s thermal energy.
4.
5. Electromagnetic Energy
This energy is transmitted
through space in electromagnetic
waves. These waves move through
empty space too, they include
visible light, x-rays, microwaves.
The Sun releases large amounts of
electromagnetic energy.
6. Nuclear Energy
The center of an atom, its nucleus , is
the source of nuclear energy. A large
amount of energy holds the nucleus
together. When the nucleus breaks apart
or when two small atoms join together,
energy is released. Nuclear energy released
from the fusing of small nuclei to form
larger nuclei keeps the Sun burning.
Kinetic Energy
Def : The energy of motion is
called kinetic energy.
You must consider the mass of the
object and the speed that the object is
moving at.
Kinetic Energy increases
as the objects mass
increases.
Example
A soccer ball and a bowling ball
The bowling ball has more
kinetic energy because it has
more mass
Potential Energy
Def : The stored energy that an
object has due to its position and
its chemical composition .
You must consider the source of
the potential energy to find how
much energy the object has.
The most obvious source of
potential energy is from
GRAVITY.
Another source of potential
energy comes from the atoms
that the object contains, the
CHEMICAL COMPOSITION.
3.2
Energy can change
forms but is never lost
Energy changes forms
Examples:
A match has stored heat and light
energy(potential energy). When the
potential energy is released
chemicals change to heat and light
energy
Plants convert Energy from the Sun
into chemical energy which is stored
as sugars in the cells
Some conversions
are obvious
Example : light bulbs
make light and heat.
Other conversions are
useful for everyday
needs
Example: Making
electric from running
water
Law of Conservation of Energy
While kicking a soccer ball the
player gives the ball energy and
the ball gains an equal amount of
that energy. The energy the ball
loses is transferred back to the
universe as sound or heat energy.
Conversions may produce
unwanted forms of energy.
In a fan :
The electric makes the fan blades turn,
it also causes heat in the motor of the fan
(unwanted /wasted of energy), it
sometimes shakes causing more
unwanted wasted energy.
If the fan is Energy Efficient it will
create more of the desired energy and
less unwanted energy.