Energy lesson 1
Objectives:
• To recall and name the forms of energy
• To be able to identify energy transfers in various situations
• To recall the principle of conservation of energy
• To realise that not all energy is usefully transferred, some
is dissipated
Energy
Energy is required to do
work.
Fuels are burnt to release
energy
The Sun is the ultimate
source of most of our energy
on Earth.
Energy makes the things around us
move or change
Forms of energy
Energy can exist in many forms.
1. THERMAL
or HEAT ENERGY
This is the energy of an
object due to its
temperature.
2. LIGHT ENERGY
This is energy in the form
of visible electromagnetic
radiation.
3. ELECTRICAL ENERGY
This is the energy
transferred by an electric
current.
4. SOUND ENERGY
This is energy in the form
of a sound wave.
5. KINETIC ENERGY
This is the energy
possessed by a moving
object.
Kinetic energy increases as
the object’s speed is
increased.
Also often called
‘Movement energy’
6. CHEMICAL ENERGY
This is energy that is released
when chemical reactions take
place.
Sources of chemical energy
include:
fuel, food and batteries.
7. NUCLEAR ENERGY
This is energy that is released
when nuclear reactions take
place.
This is the source of the
Sun’s energy.
8. POTENTIAL ENERGY
This is the energy possessed by an
object due to its position.
Gravitational Potential Energy
The gravitational potential energy of
an object increases if it is raised
upwards.
Elastic Potential Energy
This is the energy
stored in a stretched
or squashed object
- also known as strain
energy
Gravitational potential
energy being converted
into kinetic energy.
A system is an object or a group of objects.
There are changes in the way energy is stored when
a system changes
Conservation of energy
Energy cannot be created or destroyed. It
can only be transferred from one form to
another form.
Conservation of energy also means that the
total energy in the universe stays constant.
Pendulum oscillation
GRAVITATIOINAL POTENTIAL ENERGY
MAXIMUM
MINIMUM
KINETIC ENERGY
MAXIMUM
ZERO
The total energy, gravitational
potential plus kinetic, remains
the same if there are no
significant resistive forces
The pendulum does not carry on swinging for ever-why?
Useful and wasted energy
Useful energy is energy transferred to where it is
required in the form that it is wanted.
Other forms of energy are referred to as ‘wasted’.
Wasted energy spreads out into the surroundings.
We say the energy is dissipated
This is usually in the form of heat energy causing
the energy changing device and its surroundings to
become warmer. It is very difficult to ‘concentrate’
this energy again to make use of it. It can also be in
the form of sound energy
For the pendulum, work has been done against friction
and energy has been dissipated as heat energy
http://www.freezeray.com/flashFiles/bounci
ngBall.htm
15 of 32
© Boardworks Ltd 2011
https://www.youtube.com/watch?v=7FfKaIg
ArJ8
16 of 32
© Boardworks Ltd 2011