Transcript Types and Forms of Energy

What is ENERGY??
• Energy is the ability to do work or cause
change
Uses for energy:
•
•
•
•
Heat/cool houses and buildings
Provide light
Break down food
Transportation
Energy
• Energy exists in many forms.
• Energy can be moved from one
object to another.
• Energy can be changed from
one form to another.
• Energy cannot be created or
destroyed.
Potential Energy
The energy in matter due to its position or
the arrangement of its parts
Kinetic Energy
Energy of a moving object
Seven Forms of Energy
Mechanical
Heat/Thermal
Chemical
Nuclear
Electrical
Sound
Light/Radiant
Mechanical Energy
• When an object is used apply a force to
another object in order to cause it to be
displaced (or causing it to move).
• A classic example involves the massive
wrecking ball of a demolition machine.
Chemical Energy
• Energy released by a
chemical reaction
• The food you eat
contains chemical
energy that is released
when you digest your
meal
• Wood, coal, gasoline,
and natural gas are
fuels that contain
chemical energy
Heat (Thermal) Energy
• Energy created by
the motion of
atoms and
molecules that
occurs within an
object
• Thermal energy
exists when you
heat a pot of water
on a stove
Nuclear Energy
• Energy contained in the
nucleus of an atom
• Inside the reactor of an
atomic power plant,
uranium atoms are split
apart in a controlled
chain reaction to
produce electricity.
Radiant (light) Energy
• Energy from the sun that is converted to
thermal or electrical energy
• An example is solar panels providing
electricity for a home or heating water.
Sound Energy
• Audible energy
• For example when you talk, play musical
instruments or slam a door, it releases
sound energy.
Electrical Energy
• Electrical energy exists when charged
particles attract or repel each other.
• It is created by causing a turbine to turn.
• Examples heating coal to turn the turbine
to product electricity for a city.
Law of Conservation of Energy
100 J electricity in
95 J heat out
5 J light out
• The law of conservation of energy states that
energy may neither be created nor destroyed, but
can change its form.
• The sum of all the energies in the system is equal.
• An incandescent light bulb is only 5% efficient as a
lighting device. It would be more efficient as a
heater!
Law of Conservation of Energy
100 J electricity in
95 J heat out
5 J light out
• With every transformation, some
energy is converted to less useful
forms.
• Energy conversions are not 100%
efficient.
ENERGY is CONSERVED
This means that however much you
start with, you also have at the end!
Energy Conversion
All forms of energy can be converted into
other forms of energy
• It can only be TRANSFERRED.
• INPUT energy = OUTPUT energy
• Energy can be CHANGED to other
forms.
• What does “converted” mean?
Law of Conservation
of Energy
• Energy is neither CREATED or
DESTROYED.
1. Flashlight
Mechanical  chemical  radiant, thermal energy
2. Food
Mechanical  chemical  mechanical energy
3. Car
4. Television
Mechanical  electrical  chemical  mechanical,
sound, thermal energy
Mechanical  electrical  thermal, sound, light
energy
Describe all of the conversions
that would be used by your
toaster.
• Mechanical  electrical 
thermal  mechanical 
chemical
Give examples of these conversions:
• I use light
energy from the
sun to change it
into chemical
energy for me.
Give examples of these conversions:
• I use electrical
energy to make
mechanical
energy.
Figure this one out…
The following reaction shows the chemical
potential energies of the reactants and
products.
reactants
CH4 + 2O2
950kJ 50kJ
→
products
CO2 + 2H2O
35kJ
50kJ
+ energy
915 kJ