Download ME 3-3 Notes Combined

Efficiency- packet pg 37
• Efficiency- A measurement of useable energy after an
energy conversion
• The more efficient the conversion, the less energy is
wasted
• Wasted energy is energy that becomes energy forms other than the
intended form
Energy Efficiency Example
• Regular light bulbs convert electrical energy into thermal
and electromagnetic energy
• Do we intend to create thermal energy? NO!
• Some energy is converted to thermal though, and that is
less energy that can be converted to electromagnetic
energy (light!)
Regular Bulb
LED Bulb
So which is more efficient: An LED bulb or
a regular bulb?
• The LED bulb
• LED bulbs convert more electrical energy to
electromagnetic energy
• They do not “waste” as much electrical energy
• Less thermal energy is created as a byproduct
The Law of Conservation of Energy
• A law stating that no matter how energy is
transferred or transformed, it continues to
exist in one form or another
• In other words:
• Energy is not created or destroyed, just
changed from form to form
ME SECTION 3.3
NOTES
Handout
Technology Improves Energy
Conversions
• In many energy conversions, energy is wasted as
heat
• For example:
• In a “regular” light bulb, only about 5% of the electrical
energy becomes electromagnetic energy
Efficient Lights
• LED: Light Emitting Diode
• Converts almost all of the electrical energy to light
energy
• Used in:
• Remotes, computers, signs, traffic signals, etc
Efficient Cars
• Burning gasoline in cars converts chemical energy into
kinetic energy (mechanical, sound, thermal)
• Some energy is wasted as heat from the car’s engine,
tires, and breaks
• Improvements have been made to increase efficiency in
cars
• Fuel injectors and hybrid cars both have increased the
amount of kinetic energy going into the car and not into
unwanted energy (like thermal energy
Technology Improves the Use of Energy
Resources
• Much of our energy comes from fossil fuels, but
these are non-renewable resources
• Scientists are exploring many alternative energy
sources
• For example: solar energy and wind energy
Solar Energy
• Solar cells are used to trap electromagnetic
energy from the sun and convert it to electrical
energy
• Solar cells produce electrical energy quietly and
cleanly
• The sun’s radiation (electromagnetic energy) is
also used for heating (thermal energy)
Wind Energy
• Windmills are used to trap the kinetic energy from the
wind and convert it into electrical energy
Lincoln Financial Field
• The combined energy created by the solar panels and
wind turbines is more than 4 times the amount used
during one season’s home games
Energy Efficiency
• Technology has improved efficiency but…
Nothing is 100% energy
efficient!
There will always be some unwanted
energy
Energy Conversions and
Fossil Fuels- packet pg 38
Where does earth get most of it’s energy
from?
1. The sun is the major source of energy for most of
Earth’s processes
The Sun’s Nuclear Energy
2. On the sun, hydrogen atoms join and form helium- this
process is called nuclear fusion
-Electromagnetic energy is given off
3. Some of this (electromagnetic) energy reaches Earth
Then what?
4. Photosynthesis then begins on earth.
Plants grow, animals eat the plants.
5. When plants and animals die, dirt (sediment) slowly
covers them. The energy in them is now stored and
trapped within them
6. The resulting pressure along with high temperatures
turns the animal and plant remains into coal (a fossil fuel!)
Fossil Fuels
1. Include things like:
• Coal
• Petroleum
• Natural gas
What is fuel?
2. Fuel is a material that stores chemical potential
energy
• Chemical potential energy depends on…
Think back….
To the Law of Conservation of Energy
• Energy cannot be created or destroyed
• It changes form
• So where does the energy in fossil fuels come from?
Energy in fossil fuels comes from…
• The sun!
4. Fossil fuels can be burned to release the chemical
potential energy.
• (steam and heat turn turbines to produce electricity)
5. Burning fossil fuels is a process known as combustion
• The (electromagnetic) energy from the sun grew the
plants which provided (chemical) energy to animals.
When they died they were covered in soil and
compressed, forming coal and oil (chemical energy). We
burn the coal (or other fossil fuels) to create other forms of
energy!
Energy!
Problem!
• Fossil fuels are non-renewable resources!
• They take millions of years to form!