Chapter 12: Energy and Energy Resources

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Chapter 12 Energy and Energy Resources

• Carin Miranda
• 6-1
• 2007

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What is Energy?

• Energy is the ability to do work.
• Work and energy are both expressed in joules (J).

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Kinetic Energy

• Kinetic energy is the energy of motion.
• All moving objects have kinetic energy.
• Kinetic energy mass times speed squared divided
  by 2.
• The faster something is moving, the more kinetic
  energy it has.
• The more massive the object the more kinetic
  energy it has.

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Potential Energy

• Potential energy is energy based on shape or
  position.
• Gravitational potential energy is based on height
  and weight.
• The higher an object the more potential energy.
• The more massive an object the greater the
  potential energy.

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Mechanical Energy

• Mechanical energy is the total energy of motion
  and position.
• In other words it is kinetic plus potential.
• As potential goes up kinetic goes down and vice
  versa.

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Forms of energy

• Thermal (Heat)
• Chemical
• Electrical
• Sound
• Light
• Nuclear

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Thermal

• Higher temperature objects have more thermal
  energy and more kinetic energy.
• The particles in steam move faster than the
  particles in ice.
• The more particles the more thermal energy.
• A bathtub full of 75 degree water would have more
  thermal energy than a cup full of 75 degree water.

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Chemical Energy

• When particles are broken down and cannot return
  to their original form they have chemical energy.
• Examples Food, Charcoal, gasoline, firewood.

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Electrical Energy

• Moving electrons.
• Any electrical appliances or anything using
  electricity.
• Huge magnets are rotated to produce the
  electricity you use at home.

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Sound Energy

• Caused by an objects vibrations.
• It is a form of potential and kinetic energy.

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Light Energy

• Vibrations of electrically charged particles.
• Not all light energy is seen.
• Microwaves use light energy.

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Nuclear Energy

• Two or more nuclei join together (nuclear
  fusion). Example Sun
• Nucleus of an atom splits apart (nuclear
  fission). Example Uranium atoms split apart to
  produce electricity.

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Energy Conversions

• Any change from one form of energy to another.

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Kinetic to Potential

• Remember we said as potential energy goes up
  kinetic goes down and vice versa.
• Examples Person on a trampoline, pendulum, and
  wind up toys.

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Chemical Energy Conversions

• Chemical energy in food is converted into kinetic
  energy when you move.
• It is stored as potential energy when you arent
  moving.
• Where did that chemical energy come from in food?
  
• The sun gives plants light energy and they
  convert it into chemical energy.
• Batteries are another example of chemical energy.

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Electrical Energy Conversions

• Lots of examples
• Alarm clock electrical to light and sound.
• Battery chemical to electrical
• Light bulb electrical to light, thermal, and
  sometimes sound.
• Blender electrical to kinetic and sound

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Energy and Machines

• Machines make work easier by changing the size
  and/or direction of the force required to do the
  work.

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Why Conversions are Important

• Make energy useful.
• Make conversions more efficient.

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Conservation of Energy

• Friction is a force that opposes motion between
  two surfaces that are touching.
• When energy is used to overcome friction some
  energy is converted into thermal energy.
• On a roller coaster potential energy is greatest
  at the top of the biggest hill and kinetic energy
  is greatest at the bottom of the biggest hill.

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Law of Conservation of Energy

• Energy can be neither created nor destroyed.
• It can change from one form to another.
• Every time an energy conversion takes place some
  energy is always converted into thermal energy.

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Energy Resources

• A natural resource that can be converted by
  humans into another form of energy to do useful
  work.
• Can be nonrenewable or renewable.

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Nonrenewable

• Cannot be replaced easily.
• Fossil Fuels Formed from the buried remains of
  plants and animals that lived millions of years
  ago.
• Coal, petroleum, and natural gas.
• Electrical energy from fossil fuels.
• Nuclear Energy (Uranium pellets).

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Renewable

• Can be replaced over a relatively short period of
  time.
• Solar Energy (SUN).
• Energy from water (Hydroelectric).
• Wind Energy.
• Geothermal (Hot water in the ground).
• Biomass (garbage).

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Advantages and Disadvantages of Nuclear Energy

• Advantages very concentrated form of energy and
  nuclear power plants dont produce smog (CO2).
• Disadvantages Produces radioactive waste and it
  is nonrenewable.