Chapter 13 Notes: Energy Mr. Grivensky

Energy Energy is the ability to do Work or cause change Energy is measured in Joules (J) Work is done when a force is applied to move an object Power is the rate at which energy is transferred to do Work Power = Energy transferred time time

Kinetic Energy Kinetic energy is the energy of an object due to its’ motion The kinetic energy of an object depends upon 2 factors: The velocity of the object The velocity of the object The mass of the object The mass of the object Kinetic energy = ½ x Mass x Velocity 2

Calculating Kinetic Energy KE = ½ x m x v 2 A 2kg object traveling 10m/s KE= ½ x 2 x 10 2 KE= ½ x 2 x 10 2 KE = 1 x 100 = 100 Joules KE = 1 x 100 = 100 Joules The same object (2kg) traveling at 20m/s KE= ½ x 2 x 20 2 KE= ½ x 2 x 20 2 KE= 1 x 400 = 400 Joules KE= 1 x 400 = 400 Joules

Potential Energy Potential energy is stored energy that results from an object’s position Gravitational Potential Energy Gravitational Potential Energy Related to the height of an object Gravitational Potential Energy = Weight x Height See page 445 for examples See page 445 for examples Elastic Potential Energy Elastic Potential Energy Energy associated with stretching or compressing an object Examples: springs, rubber bands, bow, etc.

Forms of Energy Mechanical Energy: energy associated with the position and motion of an object Mechanical Energy = Potential Energy + Kinetic Energy Mechanical Energy = Potential Energy + Kinetic Energy Thermal Energy The total kinetic and potential energy of the particles that make up an object The total kinetic and potential energy of the particles that make up an object All objects are made up of particles that are in constant motion All objects are made up of particles that are in constant motion

Forms of Energy Electrical Energy Energy of electric charges Energy of electric charges Chemical Energy The potential energy stored in the chemical bonds between atoms of a compound The potential energy stored in the chemical bonds between atoms of a compound Nuclear Energy Energy stored in the nucleus of an atom Energy stored in the nucleus of an atom Nuclear energy is released during a nuclear reaction Nuclear energy is released during a nuclear reaction

Energy Transformations Most forms of energy can be changed from one form to another form Single transformation Single transformation Chemical energy of battery  Electrical energy Multiple transformation Multiple transformation Chemical energy (battery)  electrical energy  heat energy (light bulb)  radiant energy (light)

Conservation of Energy Energy cannot be created or destroyed It can be transformed from one type to another, but the total amount of energy always remains the same

Theory of Relativity E=mc 2 Energy = mass x (speed of light) 2 Energy = mass x (speed of light) 2 Albert Einstein’s theory explains that in some cases matter can be transformed to energy When this occurs, a huge amount of energy is released

Chapter 13: Part 2 Energy Sources

Energy and Fossil Fuels Fossil fuels A hydrocarbon deposit, such as petroleum, coal, or natural gas, derived from living matter of a previous geologic time and used for fuel Fossil fuels form underground when Carbon, which is found in all living things, is buried and subjected to the heat and pressure that exists deep below the surface of the Earth The process takes millions of years

Using Fossil Fuels 71% of all electricity generated in the United States comes from fossil fuels Of those, most power-plants run on coal, others run on natural gas or oil Fossil fuels contain chemical energy, which can be transformed into other forms of energy

Fossil Fuels  Electricity

Nuclear Power

Chain Reaction Animation Here is an animation of a Chain reaction: Nuclear Chain Reaction Animation Nuclear Chain Reaction Animation Link address: e.htm

Residential and Industrial Fuel Usage Oil38% Natural Gas24% Coal22.5% Nuclear7.5% Renewable8% Fossil Fuels (Oil, Natural Gas, and Coal) account for almost 85% of all fuels used Renewable includes: Hydropower Biofuels Geothermal Solar Wind

Using Hydropower Hydropower (Hydroelectric Power) The moving water of a stream or waterfall is passed over a turbine This kinetic energy is converted to electrical energy in a turbine The electrical energy is then sent through power lines

Biofuels Biofuel: Fuel made from biomass materials Fuel made from biomass materials Biofuels include ethanol and methanol Biofuels include ethanol and methanol Biomass Web Site Biomass Web Site Address:

Geothermal Energy a form of energy obtained from within the Earth, originating in its core; a form of energy obtained from within the Earth, originating in its core; Energy produced by extracting the Earth's internal heat Energy produced by extracting the Earth's internal heat Geothermal Energy Web Site Geothermal Energy Web Site Web Site Address:

Solar Energy Solar energy energy from the sun that is converted into thermal or electrical energy energy from the sun that is converted into thermal or electrical energy Solar energy web site Solar energy web site Web site address:

Wind Energy Wind energy Using the energy of moving air to turn turbines to produce electricity Using the energy of moving air to turn turbines to produce electricity Wind energy web site Wind energy web site Web site address:

Crude Oil Use The United States uses 500 million barrels of crude oil per month Crude oil contains: heating oil, propane, gasoline, jet fuel, diesel fuel Much of it is used as gasoline

Gasoline Gasoline is a fossil fuel that is derived from refining crude oil At a refinery, the different substances are separated by their boiling points

Gasoline Prices Graph of gasoline prices, adjusted for inflation Based on U.S. dollars for 2002