Chapter 3 Energy PDF

Chapter 3 Energy © 2022 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGra...

Chapter 3 Energy © 2022 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill. Fundamental law: Conservation of energy Manifestations: Work, motion, position, radiation (light), heat, chemical and nuclear energy, mass itself. Sources: Petroleum, coal, moving water, nuclear, solar. Uses: Transportation, generation of electricity, heating, cooling, lighting. Work 1 An applied force acting through a distance parallel to the force. Work 2 Units of work (and energy) = joule (J). W = Fd W = Fd = (pounds) = (newtons) (meters) (feet) = f t × l b = N × m = joule Work 3 Requires movement in same direction as force. o Zero distance, no work. Work 4 Displacement perpendicular to applied force, no work. Power 1 The rate at which work is done. Units: watts (W), horsepower (hp). Example: Walking versus running upstairs. The “power bill” - you pay for energy. Power 2 Motion, position and energy Work and energy related. Energy = ability to do work. Work = process of changing energy level. Access the text alternative for slide images. Potential energy Energy associated with position. Gravitational potential energy. o Measuring h - need reference height. Also: elastic (springs) and electric (charges) potential energy. Work can change PE. Kinetic energy can change into potential energy. Kinetic energy Energy associated with motion. Results from work or change in potential energy. Speed squared! (Double speed, KE increases by 4). Access the text alternative for slide images. Energy forms Mechanical energy: Electrical energy: Kinetic plus potential energy. Charges, currents, etc. Chemical energy: Nuclear energy: Energy involving the Energy involved in nucleus and nuclear chemical reactions. reactions. Radiant energy: Electromagnetic energy of light. Energy conversion 1 Any form of energy can be converted into another form. Energy flows from one form to another in natural processes. Example: pendulum. E pendulum  fixed  KE  PE Energy conversion 2 Access the text alternative for slide images. Energy conversion 3 Energy is never created or destroyed. Energy can be converted from one form to another but the total energy remains constant. Energy sources today Access the text alternative for slide images. Petroleum Oil from oil-bearing rock. Organic sediments transformed over time by bacteria, pressure and temperature. Natural gas formation similar, except at generally higher temperatures. Petroleum and natural gas often found together. Supplies are limited. Coal Accumulated plant materials, processed over time by pressure and temperature. Progression: peat to lignite to sub-bituminous to bituminous. Impurities: o Minerals lead to ash. o Sulfur leads to sulfur dioxide gas (pollutant). Petroleum, natural gas and coal = fossil fuels. Moving water Renewable with rainfall. Hydroelectric plants generate approximately 3% of US’s total energy consumption. Growth potential limited by decreasing availability of new sites. Nuclear Based on nuclear fission reactions of uranium and plutonium. Water heated in reactor and then used to produce steam to turn generating turbines. Safety of nuclear power generation is controversial. Wind Energy conversion 4 Reduces the need for additional energy consumption and saves money for the consumer. Energy efficiency improvements have significantly reduced the need for additional energy sources. The potential is still enormous for additional cost- effective energy savings and ways of preventing environmental pollution through more efficient and less- energy intensive industry and domestic practices. Modern Energy Technologies 1 Solar Cells: o Polycrystalline compounds that generate electricity when exposed to light. Active Applications: o Solar collector; sunlight heats air or liquid material. Wind Energy: o Sunlight differentially heats earth’s surface creating winds. o Wind then generates electricity. Modern Energy Technologies 2 Biomass: o Utilizes material formed by photosynthesis. Agriculture and Industrial Heating: o Utilizes sunlight rather than traditional energy sources. Ocean Thermal Energy Conversion (OTEC): Generates electricity from the temperature difference between water depths. Geothermal Energy Energy from beneath the earth’s surface: o Dry steam. o Hot water. o Hot dry rocks. o Geopressured resources. Difficulty in obtaining and economically utilizing.