ENERGY
WHAT IS ENERGY?
• Energy cannot be created or destroyed,
known as Law of Conservation Energy.
• Energy is something that must be changed or
transferred in order to do something.
• There are many types of energy stored or
transferred.
• The unit of energy is Joule (J)
ENERGY STORES AND TRANSFERS
ENERGY ENERGY STORE OF ENERGY TRANSFER
kinetic store
chemical store
thermal store or transfer
elastic potential store
gravitational potential store
electrical transfer
sound transfer
light transfer
KINETIC ENERGY is
energy of a moving
object
The amount of kinetic
energy an object has
depends on:
• the mass of the object
• the speed of the object
An object at rest (not
moving) has zero kinetic
energy
THERMAL ENERGY stored in
hot objects and transferred
to colder objects
• Sometimes thermal
energy is called heat
energy.
• Heat energy flows from
hot objects to cold
objects.
• A cup of tea “feels
warm” because it is
giving off heat energy. It
is the hot object, you
are the cold object.
ELASTIC POTENTIAL
ENERGY
• Elastic potential energy
is stored in stretched or
squashed materials.
• Some objects can
change shape when
they are pushed or
pulled. Rubber balls,
springs and elastic
bands are like this.
When an object is
stretched or squashed, Elastic potential energy is stored in this catapult
it stores elastic potential when its bands are stretched
energy. The energy is
released when it returns
to its original shape and
size.
GRAVITATIONAL
POTENTIAL ENERGY
• Gravitational potential energy
is the type of energy an object
stores due to its height above
the ground.
• When an object is lifted above
the ground, or moved higher
up, it gains gravitational
potential energy. The amount
of gravitational potential
energy an object stores These rocks store gravitational potential energy
depends on: because of their height above the ground
the mass of the object
the height above the Earth’s
surface
the gravitational field strength
CHEMICAL
ENERGY
• Chemical energy is the
energy stored in the
bonds that connect
atoms and molecules
together.
• Chemical energy is stored
in the food we eat. As the
bonds between the
atoms in food break, a
chemical reaction takes
place and energy is
released.
• Chemical energy is also
stored in fuels such as
coal, oil, natural gas,
wood and peat.
SOUND ENERGY
• Sound energy is the
energy stored in a
sound wave.
• Sound waves travel
through solids,
liquids and gases
and are produced
when an object
vibrates like a
plucked guitar
string.
LIGHT ENERGY
• Light energy is a form
of energy which our
eyes can detect.
• Light is a form of
electromagnetic
radiation and can travel
through a vacuum as
well as through solids,
liquids and gases. Light
energy travels to us
through space from the
Sun. Green plants need
light energy for
photosynthesis to
occur.
ELECTRICAL ENERGY
• Electrical energy is a
form of energy resulting
from moving electric
charges.
• Some objects carry
electrical charges. These
charged objects can
exert forces on each
other. Electrical energy
can be seen in nature in
a bolt of lightning which
is a flow of charge
Electrical energy can be seen in a bolt of lightning
through the air.
STORING ENERGY
• Uncooked rice : store chemical energy
• Coal and crude : stores of chemical energy
• Tank containing water: the water stores
gravitational potential energy
