W: What do you want to know? L: What did you learn? KWLQ What is Energy? K: What do you know? W: What do you want to know? L: What did you learn? Q: What questions do you have?

Notes: Energy

Energy is the ability to work. NOTES 98-101 Energy is the ability to work. Work is done when a force exerted on an object moves that object some distance. Work is a transfer of energy

Units are: Newtons x meters Both work and energy are measured in joules. Work & energy is force times distance Units are: Newtons x meters or Joules

Two Types of Energy Kinetic Energy Energy associated with motion Ex. Dropping the bowling ball. Potential Energy Stored energy Ex. Lifting a bowling ball to a height.

Kinetic Energy= 1/2mass X velocity squared Kinetic Energy = ½m x v²

= 180000J KE = (½ 3600Kg) X (10m/s)² Kinetic energy depends on the square velocity! So at twice the speed the truck has 4 x the energy If the truck has a mass of 3,600Kg and a velocity of 10m/s, what’s it’s Kinetic energy? A more massive truck has more kinetic energy.

Equation for Gravitational Potential energy PEgrav = mass x gravity x height or PEgrav = m x g x h

Another type of Potential Energy Elastic PE PE associated with objects that can be stretched or compressed.

Elastic Potential Energy

Gravitational Potential Energy 50Kg 10 meters high PEgrav = mass x gravity x height = 4900J PEgrav = 50Kg x 9.8m/s/s x 10m

Now calculate Kinetic Energy 50Kg Now calculate Kinetic Energy What’s its velocity if it falls for one second? Kinetic Energy = ½m x v² = 2401 J KE = (½ 50Kg) X (9.8m/s)²

Energy conversion – a change from one form of energy to another form.

Energy conversion cont… Most forms of energy can be converted into other forms Example: Mechanical energy (running water) can be converted into electrical energy (electricity)

For example burning coal at an electrical power plant converts chemical energy into heat. The heat makes steam which turns turbines mechanical energy to make electrical energy. The electrical energy is converted back into heat (oven), light (lights in the house), and mechanical energy (a car’s engine) when it is used. Gas  engine photosynthesis Food  your body Heat lamp or hair dryer Oil  electricity via power plant

Conservation of Energy Law of Conservation of Energy: when one form of energy is converted into another form of energy, no energy is destroyed in the process Energy can not be created or destroyed

Different Forms of Energy Mechanical = motion or position of an object Thermal = total energy of the particles in an object (the more energy the more heat is given off) Chemical = PE stored in chemical bonds (food)

Electrical = energy caused by moving electric charges

Electromagnetic energy = visible light, microwaves, x-rays, and uv light

Nuclear = fission and fusion

Power Power is the amount of work done in a given time. Equation for power Power = work/time or Power= force x distance/time

Power cont….. Units for Power Joules/second or… Watt (w)

Formation of fossil fuels In the earth’s crust, under distinct pressure, temperature and geological processes, nonrenewable energy formed from once living organisms.

Common Types of Fossil Fuels Coal Oil (petroleum) Natural Gas

Fossil Fuels make good fuels because the energy stored in them is abundant and easy to release when heated. Methane            CH4             (gas) Ethane              C2H6           (gas) Propane            C3H8           (gas) Butane              C4H10         (gas) Pentane             C5H12         (liquid, found in gasoline) Hexane             C6H14         (liquid, found in gasoline) Heptane            C7H16         (liquid, found in gasoline) Octane              C8H18         (liquid, found in gasoline) Pentadecane       C15H32       (liquid, found in kerosene  and jet fuel) Tetracosane       C24H50        (liquid, found in lubricating oil)

Some common uses of Crude Oil Solvents Fertilizers Pesticides Plastics Diesel fuel Jet fuel liquified petroleum gas plastics Kerosene Synthetic fibers Synthetic rubber Detergents

Source: Energy Information Administration