Gravitational energy is due to the force of gravity caused by the attraction of all other masses to the mass of the earth. As you lift an
object to a higher elevation, you give that object increased gravitational energy. You can get that energy back (or most of it) when you
drop the object and it falls to the
earth's surface. The amount of
gravitational energy that an
object possesses depends on
the object’s mass or weight, its
height above the surface, and
the strength of the field of
gravity. A heavy object will have
more gravitational potential
energy than a lighter object. An
object one mile up in the sky will
have more energy than the
same object one foot from the
surface. In addition, an object
lifted up on the Moon, which has
a weaker field of gravity than the
Earth, will have less potential
energy than the same object at a
similar height above the Earth.
Holmkollen Ski Jump
Spring energy is contained in materials and objects that can
stretch when a force is placed on them and then later return to
their original shape. A graphic of the most well known type of
spring is shown below. The spring starts at an unstretched or
equilibrium position (x=0). As the spring is stretched from this
equilibrium position, spring energy is stored in the spring. The
spring can be held until the spring is released and the spring
energy is also released. Therefore, spring energy is a form of
potential energy.
Electrical energy, for example,
is the flow of charged particles
called electrons or ions. When
electrons are flowing through a
wire or through hundreds of feet
of air (an event we call
lightning) it is because they are
being "pushed" or forced by an
electrical field. This field is
caused by a difference in
electrical charge. A force is
exerted on the electrons and
they move. Work is done on the
charged particles. A force is
pushing them through a
distance. Actually, they are
hopping from atom to atom,
being pushed by an
electromotive force. While the
electrons are moving they
contain kinetic energy. So at the
itsy-bitsy atomic level electricity
is a form of kinetic energy.
Magnetic and electrical energy are closely related
to one another. When electrons move through a
wire, a magnetic field is created around the wire. If
the wire carrying the electrons is wound around a a
metal bar of iron the iron will become magnetic and
is called an electromagnet. The magnetic energy
generated can be used to attract other metal parts
and is used in devices like the magnetic hoists used
to lift old cars into the car compactor.
Mechanical energy is the useful way
we sometimes refer to things like
gears, engines, locomotives pulling
trains, canon balls flying through the
air, or other examples of energy in
mechanical devices. But, of course,
by now you see that all these
moving parts contain kinetic energy.
They are really just different modes
of kinetic energy - the energy
contained in a moving mass. In
order to get these various objects
spinning or rolling, a force has to be
exerted. Work is a force acting
through a distance, so the way they
get moving and keep moving is by
having work done on them. Work is
an energy transfer process.
The internal energy in substances is the vibration and movement of the atoms and molecules within substances. Internal energy can be
transfered to other objects causing them to heat up. When you heat up a pan of water, the heat from the stove causes the molecules in
the pan to vibrate faster causing the pan to heat up. The internal energy from the pan causes water molecules to move faster and heat
up. So, when you heat something up, you are just making its molecules move faster.
A thermal infrared image of a ball before (left) and after (right) being bounced
There are two types of nuclear
energy, fission and fusion. Both forms
of energy are stored as mass in the
atoms of certain elements. This mass
can be changed into energy under the
proper conditions according to Albert
Einstein's famous equation. Both
types of nuclear energy can be stored,
either in the atoms of hydrogen or the
atoms of radioactive elements like
uranium. Therefore, nuclear is a
potential form of energy.
Electromagnetic energy travels in
transverse waves. Electromagnetic
energy includes visible light, x-rays,
gamma rays and radio waves. Light
is one type of electromagnetic
energy. Solar energy is an example
of electromagnetic energy.
The term chemical energy refers to energy that is stored in
molecular bonds, the forces that hold molecules together.
It is the energy due to associations of atoms in molecules and
various other kinds of aggregates of matter. It may be defined as a
work done by electric forces during re-arrangement of mutual
positions of electric charges, electrons and protons, in the process
of aggregation. So, basically it is electrostatic potential energy of
electric charges. If the chemical energy of a system decreases
during a chemical reaction, the difference is transferred to the
surroundings in some form (often heat or light); on the other hand
if the chemical energy of a system increases as a result of a
chemical reaction - the difference then is supplied by the
surroundings (usually again in form of heat or light).