Energy
How Work Gets
What is Energy?
Energy is the ability to cause
change
Two General Types of
Energy
• Potential Energy
• Kinetic Energy
What is Potential
Energy?
• Potential energy is
the energy stored in
an object.
• Examples:
– Chemical energy
stored in batteries.
– Mechanical energy
stored in a
compressed
spring, or tight
rubber band.
Gravitational Potential
Energy
• Gravitational potential energy is the
stored energy of position.
– A rock on top of a hill has more
potential energy than the same rock at
the bottom of the hill because the rock
at the top has the added energy of
being in a position where gravity can
act on it longer.
Weight (N) = mass (kg) x gravity (9.8
m/sec/sec)
What is Kinetic
Energy?
Kinetic Energy
• Kinetic energy is the
energy of motion.
• The faster something is
moving the more kinetic
energy it has.
• KE =(m x v2) / 2
Forms of Energy
•
•
•
•
Mechanical Energy
Sound Energy
Chemical Energy
Thermal “Heat”
Energy
• Electromagnetic
Energy
–Light Energy.
What is Mechanical
Energy?
• Mechanical energy is the
motion of objects.
• An example is the energy you
use to pick up a book.
What is Sound
Energy?
• Sound energy
is the vibration
of particles in a
solid, liquid, or
gas.
• Sound can not
travel through
empty space.
•
What is Electromagnetic
Energy?
Electromagnetic energy is transmitted through
space in the form of electromagnetic waves.
• Electromagnetic energy is a combination of
electrical and magnetic forces.
– Visible light is a form of electromagnetic
energy, as well as x-rays and microwaves.
– The Sun releases large amounts of
electromagnetic energy, some of which is
absorbed by Earth.
What is Electrical
Energy?
• Electrical energy comes from
the charges in atoms of
matter.
• Electrical energy is the force
of opposite charges (“+” and
“-”) attracting.
–Lightning, static, and
current are forms of
What is Magnetic
Energy?
• Magnetic energy comes from
the organization of atoms in a
material.
• Magnetic energy is the force
of opposite poles (north and
south) attracting.
What is Nuclear Energy?
Nuclear
energy
is the
energy
holding
an atom
together
.
What is Chemical
Energy?
• Chemical energy is energy that is
stored in the chemical composition
of matter.
• An example is the energy used by
cells in your body comes from the
What is Thermal
Energy?
• Thermal energy, is the energy
from the movement of
molecules.
Thermal Energy –
“Heat”
• Heat is the transfer of thermal energy
between objects.
• Heat always flows from the warmer
objects to the cooler objects.
• Temperature is the measure of how fast
the molecules of a substance are
moving. The faster the molecules
move, the higher the temperature.
Conservation of
Energy
• Energy can not be created
nor destroyed.
• Energy can be transferred
from one form to another.
Energy Transfers
• One form of energy can turn into
another form.
• An example is when a ball is thrown
(mechanical energy) against a wall,
some of this energy is converted into
sound and heat so the ball does not
bounce back as far.
• Most energy that is “wasted” in a
transfer is converted to heat energy.
•
•
•
•
•
Energy Transfers:
Remote Car
Batteries (chemical to electrical)
Electrical (electrical to electrical)
Lights flash (electrical to light)
Motor turns (electrical to mechanical)
Motor makes noise (mechanical to
sound)
• Motor gets warm (mechanical to heat)
• Wheels turn (mechanical to mechanical)
• Friction on floor (mechanical to heat and
sound)
Energy Transfers
• Wind - up
mouse
• Jack - in - the -