Download 4.1 Forms of Energy

4.1 Forms of Energy
What is energy?
—  Energy is the ability to do work.
—  We define work in a few days
—  Energy makes everything happen and can be divided
into two main types:
—  Stored energy is called potential energy.
—  Moving energy is called kinetic energy.
—  Try explaining these concepts with your pencil.
Different Forms of Energy
Form of Energy
Description
Example
Kinetic Energy
(KE)
Energy of an object due to
its motion
Vehicle in motion
Gravitational
Potential Energy
(GPE)
Energy of an object due to
its position
Book lifted up gains
GPE, a crane raises
a cargo container
Chemical Energy
Energy stored in a substance Battery, wood, oil
and released when chemical
reactions take place
Electrical Energy
Energy transferred by an
electric current
Electricity running
through wires
Elastic Strain
Energy
Energy stored in an elastic
object when we stretch or
squash it
Stretched Spring,
rubber band
Different Forms of Energy
Note: the energy of
an object due to its
temperature is
sometimes called
thermal energy
Form of Energy
Description
Example
Nuclear Energy
Energy released when the
nucleus of an atom splits or
disintegrates
A uranium fuel rod
in a nuclear reactor
Internal Energy
Energy of an object due to
the internal motion and
positions of its molecules
Magnetized object
or a hot object
Heat Energy
Energy transfer from a hot
object to a cold object
heat radiation from
burning coals
Sound Energy
Energy transfer by sound
waves
Sound from a drum
Light Energy
Energy transfer by light
Light from a
flashlight
Energy Transformations
—  Energy Transformations: when energy changes from
one form into another.
Energy Transfer Example
An athlete performing a pole-vault:
1.  Uses his or her muscles to convert
chemical energy into kinetic energy
and elastic strain energy of the pole.
2.  This is then transformed into GPE and also produces
heat energy and sound energy
Chemical Energy
Kinetic Energy + Elastic energy
GPE + thermal energy + sound
energy
Energy Transfer Example
A pile driver on a building site: Lifts a
heavy steel block above the
top end of the girder then lets it
crash down onto the girder.
GPE
Kinetic Energy
thermal energy + sound energy
Summary Questions
GPE
1.  When a ball falls in the air, it loses __________
energy
and gains __________
energy.
KE
2.  When an electric heater is switched on, it changes
electrical
thermal +heat
__________
energy into __________
energy.
3.  List two different objects you could use to light a room
in the event of a power outage. For each object,
describe the energy changes that happen when it
produces light.