DOCSLIB.ORG

Science of Energy I

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Science of Energy I .edu /~ Page metin 1 Science of Energy utdallas Traditional Forms of Energy Potential Energy Kinetic Energy Thermal Energy .edu /~ Page metin 2 Forms of Energy utdallas Fundamental law of Science: Energy and mass are conserved. – You cannot waste energy even if you want. – Wasting energy is actually transforming energy to an undesirable form Forms of Energy: – Traditional Energy: Potential, Kinetic and Thermal – Fuel-Based Energy: Chemical and Nuclear – Electromagnetic Energy: Electric and Magnetic Energy generation is actually energy transformation from one form to another – Dropping a pen: Potential Kinetic – Rubbing hands: Kinetic Thermal – Boiling water rises: Thermal→ Potential → → .edu /~ Page metin 3 Potential Energy utdallas Gravitational force = Weight Weight = Mass m Gravitational acceleration constant g – Mass in kilogram (kg); Acceleration constant in metres per square second (m/s ) – Then gravitational force in∗ Newton = kg x m/s 2 – Ex: What is the weight (gravitational force applying2 to) of a person with 80 kilogram mass? » The weight is 784=80(9.8) kilogram meters per square second or 784 newtons. Potential Energy Potential Energy = Gravitational force mg x Height h – Gravitational force in Newton & Height in meters Potential energy in Joule = Newton x metre – Ex: What is the potential energy gained by a person with 80 kg mass walking stairs up for 10 metres? Would your answer change if the person takes⇒ an elevator? » It is 80(9.8)10 kg square meters per square second or simply 7,840 joule. Comparison between metric and imperial units Mass Gravitational Acceleration g Force Metric Kilogram kg 9.81 Metre per (second * second) m/s Newton N Imperial Slug s 1.00 Feet per (second * second) ft/s 2 Pound force lbf Imperial Pound mass lbm 32.20 Feet per (second * second) ft/s2 Pound force lbf 1 kg = 0.068 s = 2.20 lbm. 14.65 kg = 1 s = 32.2 lbm. 0.45 kg= 20.031 slug = 1 lbm. Roughly Slug:Kilogram:Pound force ratios are 32 : 2 : 1. If you never hear ofslug wonder& where it is used, check crossword puzzles. .edu /~ Page metin 4 Kinetic Energy utdallas Drop an object of mass from a height of , which takes time Initial speed 0 & final speed at the bottom , average speed /2 ℎ We must have =Distance=Average speed Time= Furthermore, potential energy becomes kinetic energy at the bottom ℎ ∗ 2 Potential Energy = = = = Kinetic energy 1 2 ℎ 2 2 Kinetic energy is proportional to the mass & square of the speed from above. In general, Kinetic energy= , where is the speed 1 Ex: An accounting book weighs2 1 kg and is dropped from 1 metre, what is its kinetic energy at the 2 bottom of the drop? – By using the conservation of energy, we can say the kinetic energy gained is equal to the potential energy lost, which is mgh=1(9.8)1=9.8 joule. Ex: Consider a horizontal cylinder which is subject to air flow from left to right. There is a propeller at the right-hand side of the cylinder. The air flow passes 75% of its kinetic energy to the propeller to rotate it. Assuming that the energy conversion is perfect (no energy is lost when air flow's kinetic energy is passed to the propeller), how much does the air flow slows down after passing through the propeller? – The kinetic energy of each incoming air particle is 2 at the entry and = = 2 at the exit for = . 2 2 3 1 2 1 Hence, air particles lose half of their speed after transferring2 their energy to the propeller. 2 − 4 2 2 2 2 2 .edu /~ Page metin 5 Thermal Energy utdallas Thermal Energy Thermal Energy = Mass Heat capacity constant Temperature Mass is in kilogram Heat capacity constant is in joule per (kilogram ∗ x celsius) or joule per (kilogram ∗ x kelvin) Sometimes temperature is measured in kelvin; 0 kelvin is 273 celsius − Heat capacity constant is the ability of a substance to absorb thermal energy For water 4200 joule per (kilogram x celsius) > For sand 835 joule per (kilogram x celsius) Ex: To increase the temperature of 0.33 kilogram (330 millilitre, can soda size) of water by 50 celsius, how much thermal energy is needed? – The energy needed for water is 0.33(4200)50=69,300 joules. For storage and transportation of energy, the industry needs substances with high heat capacity such as water and molten salts. 1 calorie = 4.2 joule & increases the temperature of 1 gram water by 1 Celsius Ex: A cafeteria sells 1000 calorie salads. How many meters a person with 80 kg mass can climb with this amount of energy? – 1000 calorie = 4200 joule, which is the potential energy of 80 kg person at 5.35 metres = 4,200/(80 * 9.8). – To burn a salad, is it sufficient to climb two floors of a building?? – No! Dieticians use calorie to mean kilocalories. The salad actually has 1,000,000 calories which can be burnt by climbing a mountain of 5350 metres! .edu /~ Page metin 6 Summary utdallas Potential Energy Kinetic Energy Thermal Energy .edu /~ Page Which Empire had Imperial Units? metin 7 A lot of them! utdallas British Empire Handle with hook – British used pound as the unit of mass. for suspension – Not only one, but many pounds in use: » London Pound » Merchant Pound » Tower Pound » Troy Pound » Avoir-du-pois (goods-of-weight in French) Pound Cup – But these are all shortened as lb, why? A chain with head of French Empire youthful Mercury » Livre esterin » Livre de Paris Bronze Balance, Naples, » Livre metrique Museo Archeologico Nazionale. Pfund in Prussian Empire Libra Pondo Pond in the Netherlands Funt in Russian Empire lb Pund (Skal)Pund in Swedish Empire Litra Funt Litra in Byzantine Empire Litre for volume now Litre Pond Libra Pondo (weights of weighing) in Roman Empire. → Livre Libra is shortened as lb. Ponderis: To weigh in Latin. Pfund Linguistic Insight: Words “Pound” & “Ponder” are relatives. Pound.
Load more

Recommended publications
  • 5 Military Rucking Rules Every Backpacker Should Know 1. One
    5 Military Rucking Rules Every Backpacker Should Know The military has spent years studying the best way to move under a load (aka “rucking”). Here are 5 military rucking rules that translate well to hikers. “Rucking” is the military term for hiking under load. As you can imagine, this is a huge issue for the military, as soldiers must wear body armor and carry weapons, ammo, water, communications equipment, and other gear as they conduct patrols and missions. Rucking performance and injury prevention are hugely important for military operations and personnel. Movement over ground under load is also a key for hiking and backpacking. In reviewing the research the military has already done on this subject, we discovered five rules. Read on to make sure you’re following these military rucking rules on your next backcountry adventure. 1. One pound on your feet equals five pounds on your back. This old backpacking thumb rule holds true, according to a 1984 study from the U.S. Army Research Institute. They tested how much more energy was expended with different footwear (boots and shoes) and concluded that it take 4.7 to 6.4 times as much energy to move at a given pace when weight is carried on the shoe versus on the torso. In practical terms, this means you could carry half a gallon more of water (a little over 4 pounds) if you buy boots that are a pound lighter, which isn’t hard to do; and that’s a lot of water. Now imagine the energy savings of backpacking in light trail running shoes rather than heavy, leather backpacking boots over the course of 7- day backpacking trip.
    [Show full text]
  • Conversion Factor Table Copyright © by Jon Wittwer
    Conversion Factor Table http://www.et.byu.edu/~jww8 Copyright © by Jon Wittwer Multiple by To Get hp 2544.5 Btu / hr m / s 3.60 km / h inch 2.54 cm hp 745.70 W (watt) m / s 3.2808 ft / s This can also be written as: 1 inch = 2.54 cm hp 0.74570 kW m / s 2.237 mi / h (mph) A acre 43,560 ft2 hp 33,000 ft·lbf / min m / s2 3.2808 ft / s2 ampere·hr (A·h) 3,600 coulomb (C) hp 550 ft·lbf / sec metric ton 1000 kg hp·hr 2544 Btu ångström (Å) 1x10-10 m mil 0.001 in 6 atm (atmosphere) 1.01325 bar hp·hr 1.98x10 ft·lbf mi (mile) 5280 ft atm, std 76.0 cm of Hg hp·hr 2.68x106 J mi 1.6093 km atm, std 760 mm of Hg at 0ºC in 2.54* cm mi2 (square mile) 640 acres atm, std 33.90 ft of water in of Hg 0.0334 atm mph (mile/hour) 1.6093 km / hr atm, std 29.92 in of Hg at 30ºF in of Hg 13.60 in of water mph 88.0 ft / min (fpm) atm, std 14.696 lbf/in2 abs (psia) in of Hg 3.387 kPa mph 1.467 ft / s atm, std 101.325 kPa in of water 0.0736 in of Hg mph 0.4470 m / s 2 -6 atm, std 1.013x105 Pa in of water 0.0361 lbf / in (psi) micron 1x10 m in of water 0.002458 atm -3 atm, std 1.03323 kgf / cm2 mm of Hg 1.316x10 atm -4 atm, std 14.696 psia J J (joule) 9.4782x10 Btu mm of Hg 0.1333 kPa B bar 0.9869 atm, std J 6.2415x1018 eV mm of water 9.678x10-5 atm bar 1x105 Pa J 0.73756 ft·lbf N N (newton) 1 kg·m / s2 J1N·m Btu 778.169 ft·lbf N 1x105 dyne 7 Btu 1055.056 J J 1x10 ergs µN (microN) 0.1 dyne Btu 5.40395 psia·ft3 J / s 1 W N 0.22481 lbf K kg (kilogram) 2.2046226 lbm (pound mass) Btu 2.928x10-4 kWh N·m 0.7376 ft·lbf -5 kg 0.068522 slug N·m 1 J Btu 1x10 therm -3 kg 1x10 metric
    [Show full text]
  • An Atomic Physics Perspective on the New Kilogram Defined by Planck's Constant
    An atomic physics perspective on the new kilogram defined by Planck’s constant (Wolfgang Ketterle and Alan O. Jamison, MIT) (Manuscript submitted to Physics Today) On May 20, the kilogram will no longer be defined by the artefact in Paris, but through the definition1 of Planck’s constant h=6.626 070 15*10-34 kg m2/s. This is the result of advances in metrology: The best two measurements of h, the Watt balance and the silicon spheres, have now reached an accuracy similar to the mass drift of the ur-kilogram in Paris over 130 years. At this point, the General Conference on Weights and Measures decided to use the precisely measured numerical value of h as the definition of h, which then defines the unit of the kilogram. But how can we now explain in simple terms what exactly one kilogram is? How do fixed numerical values of h, the speed of light c and the Cs hyperfine frequency νCs define the kilogram? In this article we give a simple conceptual picture of the new kilogram and relate it to the practical realizations of the kilogram. A similar change occurred in 1983 for the definition of the meter when the speed of light was defined to be 299 792 458 m/s. Since the second was the time required for 9 192 631 770 oscillations of hyperfine radiation from a cesium atom, defining the speed of light defined the meter as the distance travelled by light in 1/9192631770 of a second, or equivalently, as 9192631770/299792458 times the wavelength of the cesium hyperfine radiation.
    [Show full text]
  • Energetics of a Turbulent Ocean
    Energetics of a Turbulent Ocean Raffaele Ferrari January 12, 2009 1 Energetics of a Turbulent Ocean One of the earliest theoretical investigations of ocean circulation was by Count Rumford. He proposed that the meridional overturning circulation was driven by temperature gradients. The ocean cools at the poles and is heated in the tropics, so Rumford speculated that large scale convection was responsible for the ocean currents. This idea was the precursor of the thermohaline circulation, which postulates that the evaporation of water and the subsequent increase in salinity also helps drive the circulation. These theories compare the oceans to a heat engine whose energy is derived from solar radiation through some convective process. In the 1800s James Croll noted that the currents in the Atlantic ocean had a tendency to be in the same direction as the prevailing winds. For example the trade winds blow westward across the mid-Atlantic and drive the Gulf Stream. Croll believed that the surface winds were responsible for mechanically driving the ocean currents, in contrast to convection. Although both Croll and Rumford used simple theories of fluid dynamics to develop their ideas, important qualitative features of their work are present in modern theories of ocean circulation. Modern physical oceanography has developed a far more sophisticated picture of the physics of ocean circulation, and modern theories include the effects of phenomena on a wide range of length scales. Scientists are interested in understanding the forces governing the ocean circulation, and one way to do this is to derive energy constraints on the differ- ent processes in the ocean.
    [Show full text]
  • Work and Energy Summary Sheet Chapter 6
    Work and Energy Summary Sheet Chapter 6 Work: work is done when a force is applied to a mass through a displacement or W=Fd. The force and the displacement must be parallel to one another in order for work to be done. F (N) W =(Fcosθ)d F If the force is not parallel to The area of a force vs. the displacement, then the displacement graph + W component of the force that represents the work θ d (m) is parallel must be found. done by the varying - W d force. Signs and Units for Work Work is a scalar but it can be positive or negative. Units of Work F d W = + (Ex: pitcher throwing ball) 1 N•m = 1 J (Joule) F d W = - (Ex. catcher catching ball) Note: N = kg m/s2 • Work – Energy Principle Hooke’s Law x The work done on an object is equal to its change F = kx in kinetic energy. F F is the applied force. 2 2 x W = ΔEk = ½ mvf – ½ mvi x is the change in length. k is the spring constant. F Energy Defined Units Energy is the ability to do work. Same as work: 1 N•m = 1 J (Joule) Kinetic Energy Potential Energy Potential energy is stored energy due to a system’s shape, position, or Kinetic energy is the energy of state. motion. If a mass has velocity, Gravitational PE Elastic (Spring) PE then it has KE 2 Mass with height Stretch/compress elastic material Ek = ½ mv 2 EG = mgh EE = ½ kx To measure the change in KE Change in E use: G Change in ES 2 2 2 2 ΔEk = ½ mvf – ½ mvi ΔEG = mghf – mghi ΔEE = ½ kxf – ½ kxi Conservation of Energy “The total energy is neither increased nor decreased in any process.
    [Show full text]
  • Innovation Insights Brief | 2020
    FIVE STEPS TO ENERGY STORAGE Innovation Insights Brief | 2020 In collaboration with the California Independent System Operator (CAISO) ABOUT THE WORLD ENERGY COUNCIL ABOUT THIS INSIGHTS BRIEF The World Energy Council is the principal impartial This Innovation Insights brief on energy storage is part network of energy leaders and practitioners promoting of a series of publications by the World Energy Council an affordable, stable and environmentally sensitive focused on Innovation. In a fast-paced era of disruptive energy system for the greatest benefit of all. changes, this brief aims at facilitating strategic sharing of knowledge between the Council’s members and the Formed in 1923, the Council is the premiere global other energy stakeholders and policy shapers. energy body, representing the entire energy spectrum, with over 3,000 member organisations in over 90 countries, drawn from governments, private and state corporations, academia, NGOs and energy stakeholders. We inform global, regional and national energy strategies by hosting high-level events including the World Energy Congress and publishing authoritative studies, and work through our extensive member network to facilitate the world’s energy policy dialogue. Further details at www.worldenergy.org and @WECouncil Published by the World Energy Council 2020 Copyright © 2020 World Energy Council. All rights reserved. All or part of this publication may be used or reproduced as long as the following citation is included on each copy or transmission: ‘Used by permission of the World
    [Show full text]
  • Hydroelectric Power -- What Is It? It=S a Form of Energy … a Renewable Resource
    INTRODUCTION Hydroelectric Power -- what is it? It=s a form of energy … a renewable resource. Hydropower provides about 96 percent of the renewable energy in the United States. Other renewable resources include geothermal, wave power, tidal power, wind power, and solar power. Hydroelectric powerplants do not use up resources to create electricity nor do they pollute the air, land, or water, as other powerplants may. Hydroelectric power has played an important part in the development of this Nation's electric power industry. Both small and large hydroelectric power developments were instrumental in the early expansion of the electric power industry. Hydroelectric power comes from flowing water … winter and spring runoff from mountain streams and clear lakes. Water, when it is falling by the force of gravity, can be used to turn turbines and generators that produce electricity. Hydroelectric power is important to our Nation. Growing populations and modern technologies require vast amounts of electricity for creating, building, and expanding. In the 1920's, hydroelectric plants supplied as much as 40 percent of the electric energy produced. Although the amount of energy produced by this means has steadily increased, the amount produced by other types of powerplants has increased at a faster rate and hydroelectric power presently supplies about 10 percent of the electrical generating capacity of the United States. Hydropower is an essential contributor in the national power grid because of its ability to respond quickly to rapidly varying loads or system disturbances, which base load plants with steam systems powered by combustion or nuclear processes cannot accommodate. Reclamation=s 58 powerplants throughout the Western United States produce an average of 42 billion kWh (kilowatt-hours) per year, enough to meet the residential needs of more than 14 million people.
    [Show full text]
  • Guide for the Use of the International System of Units (SI)
    Guide for the Use of the International System of Units (SI) m kg s cd SI mol K A NIST Special Publication 811 2008 Edition Ambler Thompson and Barry N. Taylor NIST Special Publication 811 2008 Edition Guide for the Use of the International System of Units (SI) Ambler Thompson Technology Services and Barry N. Taylor Physics Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899 (Supersedes NIST Special Publication 811, 1995 Edition, April 1995) March 2008 U.S. Department of Commerce Carlos M. Gutierrez, Secretary National Institute of Standards and Technology James M. Turner, Acting Director National Institute of Standards and Technology Special Publication 811, 2008 Edition (Supersedes NIST Special Publication 811, April 1995 Edition) Natl. Inst. Stand. Technol. Spec. Publ. 811, 2008 Ed., 85 pages (March 2008; 2nd printing November 2008) CODEN: NSPUE3 Note on 2nd printing: This 2nd printing dated November 2008 of NIST SP811 corrects a number of minor typographical errors present in the 1st printing dated March 2008. Guide for the Use of the International System of Units (SI) Preface The International System of Units, universally abbreviated SI (from the French Le Système International d’Unités), is the modern metric system of measurement. Long the dominant measurement system used in science, the SI is becoming the dominant measurement system used in international commerce. The Omnibus Trade and Competitiveness Act of August 1988 [Public Law (PL) 100-418] changed the name of the National Bureau of Standards (NBS) to the National Institute of Standards and Technology (NIST) and gave to NIST the added task of helping U.S.
    [Show full text]
  • Multidisciplinary Design Project Engineering Dictionary Version 0.0.2
    Multidisciplinary Design Project Engineering Dictionary Version 0.0.2 February 15, 2006 . DRAFT Cambridge-MIT Institute Multidisciplinary Design Project This Dictionary/Glossary of Engineering terms has been compiled to compliment the work developed as part of the Multi-disciplinary Design Project (MDP), which is a programme to develop teaching material and kits to aid the running of mechtronics projects in Universities and Schools. The project is being carried out with support from the Cambridge-MIT Institute undergraduate teaching programe. For more information about the project please visit the MDP website at http://www-mdp.eng.cam.ac.uk or contact Dr. Peter Long Prof. Alex Slocum Cambridge University Engineering Department Massachusetts Institute of Technology Trumpington Street, 77 Massachusetts Ave. Cambridge. Cambridge MA 02139-4307 CB2 1PZ. USA e-mail: [email protected] e-mail: [email protected] tel: +44 (0) 1223 332779 tel: +1 617 253 0012 For information about the CMI initiative please see Cambridge-MIT Institute website :- http://www.cambridge-mit.org CMI CMI, University of Cambridge Massachusetts Institute of Technology 10 Miller’s Yard, 77 Massachusetts Ave. Mill Lane, Cambridge MA 02139-4307 Cambridge. CB2 1RQ. USA tel: +44 (0) 1223 327207 tel. +1 617 253 7732 fax: +44 (0) 1223 765891 fax. +1 617 258 8539 . DRAFT 2 CMI-MDP Programme 1 Introduction This dictionary/glossary has not been developed as a definative work but as a useful reference book for engi- neering students to search when looking for the meaning of a word/phrase. It has been compiled from a number of existing glossaries together with a number of local additions.
    [Show full text]
  • Measuring in Metric Units BEFORE Now WHY? You Used Metric Units
    Measuring in Metric Units BEFORE Now WHY? You used metric units. You’ll measure and estimate So you can estimate the mass using metric units. of a bike, as in Ex. 20. Themetric system is a decimal system of measurement. The metric Word Watch system has units for length, mass, and capacity. metric system, p. 80 Length Themeter (m) is the basic unit of length in the metric system. length: meter, millimeter, centimeter, kilometer, Three other metric units of length are themillimeter (mm) , p. 80 centimeter (cm) , andkilometer (km) . mass: gram, milligram, kilogram, p. 81 You can use the following benchmarks to estimate length. capacity: liter, milliliter, kiloliter, p. 82 1 millimeter 1 centimeter 1 meter thickness of width of a large height of the a dime paper clip back of a chair 1 kilometer combined length of 9 football fields EXAMPLE 1 Using Metric Units of Length Estimate the length of the bandage by imagining paper clips laid next to it. Then measure the bandage with a metric ruler to check your estimate. 1 Estimate using paper clips. About 5 large paper clips fit next to the bandage, so it is about 5 centimeters long. ch O at ut! W 2 Measure using a ruler. A typical metric ruler allows you to measure Each centimeter is divided only to the nearest tenth of into tenths, so the bandage cm 12345 a centimeter. is 4.8 centimeters long. 80 Chapter 2 Decimal Operations Mass Mass is the amount of matter that an object has. The gram (g) is the basic metric unit of mass.
    [Show full text]
  • Energy and Energy Transformations Transformations Energy
    Energy and Energy Transformations Energy Transformations Key Concepts • What is the law of conservation of energy? What do you think? Read the three statements below and decide • How does friction affect whether you agree or disagree with them. Place an A in the Before column if you agree with the statement or a D if you disagree. After you’ve read this energy transformations? lesson, reread the statements to see if you have changed your mind. • How are different types of energy used? Before Statement After 4. Energy can change from one form to another. 5. Energy is destroyed when you apply the brakes on a moving bicycle or a moving car. 6. The Sun releases radiant energy. Identify Main Ideas Highlight the sentences in Changes Between Forms of Energy this lesson that talk about Have you ever made popcorn in a microwave oven to eat how energy changes form. while watching television? Energy changes form when you Use the highlighted make popcorn, as shown in the figure below. A microwave Companies, Inc. The McGraw-Hill of a division © Glencoe/McGraw-Hill, Copyright sentences to review. oven changes electric energy into radiant energy. Radiant energy changes into thermal energy in the popcorn kernels. Visual Check These changes from one form of energy to another are 1. Identify Which energy called energy transformations. As you watch TV, energy transformation pops the transformations occur in the television. A television corn kernels? transforms electric energy into sound energy and radiant energy. Energy Transformation 1 2 Electric energy is transferred from the The microwave oven electrical outlet to the microwave.
    [Show full text]
  • From Atoms to Electricity
    STEM PROJECT STARTER Transform Energy Topic From Atoms to Electricity PROJECT DETAILS Overview Course This project provides students with the opportunity to synthesize what they have Physical Science learned about energy transformation in other power systems to develop a model that describes the energy conversions in a nuclear power plant. Nuclear power Grade Span plants work by using the heat from fission to create mechanical energy, which turns 6-8 an electric generator. This heat is used to make steam, that turns a turbine, and Duration then turns the generator. Nuclear power is the only energy source with near-zero x2 45–60-minute sessions carbon emissions that can sustainably deliver energy to our industrial society. Concept Transformation of Energy Essential Question How does the energy stored in an atom’s nucleus transform into the electricity that powers our lives? Materials • Image of nuclear power plant • Projector to display video • From Atom to Electricity Rubrics student handout • Chart paper for students to sketch their diagram • Nuclear Power Plant Diagram student handout (optional) Procedure Think Energy n Display an image of a nuclear power plant. 1 Transform Energy Microsite | From Atoms to Electricity Encourage students to look closely and try to observe as many details as possible. o Give students five minutes to jot down answers to the following questions: • What do you see? Remind students to only report on things they actually see in the image. • What do you think about that? • What does it make you wonder? • Facilitate a group discussion about the questions. • Ask students to use the following stems when sharing: “I see...,” “I think...,” “I wonder....” Prior to watching/reading/listening to the video below, divide students into teams of four students and assign each a p perspective ‘hat’ to take while watching the content: a.
    [Show full text]