2 EnergyDefined as the ability to do work or the ability to cause change.
3 Two types of energy:Kinetic energy- energy of motion; anything that moves has kinetic energy, cars, balls, and even atoms.Potential energy- stored energy; sometimes called energy of position, anything not moving has potential energy
4 Swinging Pendulum P.E. is greatest here, P.E. is greatest here, K.E. = 0P.E. is greatest here,K.E. = 0Kinetic energy isgreatest here, P.E. =0
5 Kinetic energyThe amount of kinetic energy an object has depends on two things:1. mass2. velocityK.E. = 1/2mv½ (mass X velocity squared)2
6 Potential EnergyThis is the energy that something that is not moving has the potential of having.Potential energy depends on:1. mass2. position (height and gravity)P.E. = mgh (mass X gravity X height)
7 Forms of energy Thermal Chemical Light Sound Electrical Nuclear All forms of energy have kinetic and/or potential energy.
8 Thermal energyHeat energy- all objects have thermal energy; it increases as temperature increases.Which has more thermal energy? Why?
9 Chemical EnergyEnergy stored in chemical bonds; includes the food we eat.
11 Sound energyEnergy caused by vibrations; some of these vibrations we can hear.
12 Electrical energyEnergy that is carried by an electric current (a path that electrons follow).
13 Nuclear EnergyEnergy from the nucleus of an atom
14 Energy Transformations Change from one form of energy to another.Always produces thermal energy (heat).
15 Examples of energy transformations Photosynthesis (light to chemical)Digestion of food (chemical to mechanical)Burning of fuel (chemical to mechanical and thermal)Electrical to light and thermal (light bulb)
16 Law of Conservation of Energy States that energy cannot be created or destroyed, only transferred or changed from one form to another.
17 Kinetic and Potential Energy Kinetic energy and potential energy can be transferred back and forth as seen in a swinging pendulum or throwing a ball up.
18 Transforming Chemical Energy Can be seen as chemical reactions occur in living things causing bonds to be broken and kinetic energy (contraction of a muscle) to be formed.Decomposition of dead or decaying matter.
19 Transforming Electrical Energy Electrical energy can be transformed to sound energy (listening to the radio)Electrical energy can be transformed to chemical energy (neurons “fire” and release chemicals)
20 Transforming Thermal Energy Thermal energy can be changed to mechanical energy (steam used to move locomotives)Thermal energy can be transformed to light (radiant) energy (glowing metal on stove)
21 Generating Electrical Energy Generator- device that transforms kinetic energy into electrical energyTurbines- set of steam powered fan blades that spins a generator at a power plant.
22 Electric Power PlantsPower plants- most power plants use energy from coal to start the transformation of energy similar to below.ChemicalEnergy ofCoalKineticEnergy ofSteamThermalEnergy ofWaterKinetic energyOf turbineElectricalEnergy
23 Sources of Energy Energy that we use comes from two main sources: Renewable resources- resources that can be replacedNonrenewable resources- resources that cannot be replaced
24 Nonrenewable Resources Fossil Fuels- formed from the remains of once living things.- energy from these can be traced back to the sun through the food chain
25 Fossil Fuels- there are three main types of fossil fuels Coal- formed from the remains of plants that once lived on landPetroleum-(crude oil) formed from the remains of microscopic organisms in the oceans.Natural gas- sometimes found along with deposits of petroleum; also formed from ancient ocean microscopic life
26 CoalPrimarily used for generating electricity; also used for paper production and iron and steel production.Coal is mined from deposits in two methods:Surface miningUnderground minin
27 PetroleumRefining petroleum produces gasoline, kerosene, asphalt and petrochemical products such as plastics; some perfumes and insecticides are made from products of crude oil
28 Natural gas (methane)Natural gas is used to heat ( and in some cases cool) homes and other buildings; also used for generating electricityBurns the cleanest of the fossil fuelsCan be produced- (by-product of decaying organic matter)
29 What’s so bad about these fossil fuels? Energy crisis – result of over dependence on fossil fuelsBurning fossil fuels releases sulfur dioxide which mixes with rain and causes acid rainBurning fossil fuels also releases carbon dioxide which contributes to the greenhouse effect
30 Nuclear energyEnergy from fission (splitting of the atom) can be converted to other sources of energy such as electricityNegatives- produces radiation that has to be contained; Uranium is nonrenewable
31 Renewable Resources Solar energy Geothermal energy Tidal energy Wind energyHydroelectric energyBiomass
32 Solar energy- energy from the sun Collected by thermal collectors (roofs) or photovoltaic cells (calculators, roofs, satellites)
33 Geothermal energy- heat from deep inside the earth is used as an energy source
34 Wind energy- windmills convert kinetic energy to electrical energy
35 Hydroelectric energyWater that is behind a dam can be used to move turbines and generate electricity.
36 Tidal energyEnergy from the ocean tides can be used to generate electricity.
37 BiomassEnergy from living things (primarily plants) can be used for fuel.