NUCLEAR POTENTIAL
ENERGY
The energy stored in the nucleus of an atom is
called nuclear energy there are two possible
chemical reactions to obtain nuclear energy:
(1)Fission Reaction: Splitting of atom is called fission.
When a heavy nucleus such as uranium is broken down
into small daughter nuclei an amount of energy is
released as heat and light
(2) Fusion Reaction: Fusion is opposite of fission i.e.
you join atoms together When small daughter nulei
merge together they will form a big parent nucleus
and store huge amount of energy. This reaction can
only take place on the surface of sun in which
hydrogen atoms combine to form helium.
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INTERNAL ENERGY
•The internal energy of a substance
is defined as:
•The sum of the random
distribution of kinetic and
potential energies within a system
of atoms and molecules
MECHANICAL ENERGY
Internal energy is the microscopic
energy within a system, whereas
mechanical energy is the
macroscopic energy associated with
the visible movement of an object.
Mechanical energy is the energy that is
possessed by an object due to its
motion or due to its position.
Emech = Ek + Eg
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THE PRINCIPLE OF CONSERVATION OF ENERGY
‘Energy cannot be created or destroyed; it
can only be transformed from one form to
another’
➢This means the total amount of energy in a closed system remains
constant.
➢Therefore, energy cannot be ‘lost’, but it can be transferred to the
surroundings
 Energy can be dissipated (spread out) to the surroundings by heating and radiation
 Dissipated energy transfers are often not useful, in which case they can be described
as wasted energy
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ENERGY CONVERSIONS
TOTAL AMOUNT OF ENERGY OF A CLOSED SYSTEM REMAINS CONSTANT.
EXAMPLES
1. television:
electrical energy ➝ light energy + sound energy + thermal energy
Light and sound energy are useful energy transfers whereas thermal energy (from
the heating up of wires) is wasted
2. heater:
electrical energy ➝ thermal energy + sound energy
The thermal energy is useful, whereas sound is not
·
·
·
3. A battery connected to a bulb
chemical energy ➝ electrical energy ➝ light energy + thermal energy
·
4. A falling object (in a vacuum):
gravitational potential energy ➝ kinetic energy
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ENERGY FLOW DIAGRAMS
•Energy stores and transfers can be represented using a flow diagram
• This shows both the stores and the transfers taking place within a
system
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SANKEY
DIAGRAMS
Sankey diagrams can be used to represent energy
transfers. They are characterised by arrows that split to
show the proportions of the energy transfers taking place
•The different parts of the arrow in a Sankey
diagram represent the different energy
transfers:
• The left-hand side of the arrow (the flat end)
represents the energy transferred into the
system
• The straight arrow pointing to the right
represents the energy that ends up in the
desired store; this is the useful energy output
• The arrows that bend away represent
the wasted energy
•The width of each arrow is proportional to the
amount of energy being transferred
•As a result of the conversation of energy:
total energy in = total energy out
total energy in = useful energy out + wasted energy
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SANKEY DIAGRAMS FOR AN ENERGY
EFFICIENT BULB AND A FILAMENT BULB
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SANKEY DIAGRAM
~
-
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SANKEY DIAGRAM
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LET’S PRACTICE
Total
input
5005
500
Waste
-
=
=
120
-
Total output
120 + Waste
=
Waste
3805
-
qapapor
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