ENERGY 1 ENERGY UNITS Energy: The ability to do work (make - PowerPoint PPT Presentation

ENERGY 1

ENERGY UNITS  Energy: The ability to do work (make something happen)  Joule (J)  Calorie (cal)  The calories on food packages are really kcal  Electron Volt (eV)  British Thermal Unit (btu)  Kilo watt hours ( kW·h ) 1 cal 4.184 J 1 eV 1.620×10 -19 J 1 btu 1055 J 3.600×10 6 J 1 kW·h  Your body gets 8,000 J (1,900 cal = 1.9 kcal) of energy from eating a peanut.  6O J of energy are need per second to keep a 60 W appliance running.  1 gallon of gas produces 1.32×10 8 J of energy or enough energy to keep a 60 W appliance running for 25 days. 2

WORK  Work (J)  Work is always a change in energy. How much energy it took to do ____________. 3

POWER  Power ( 𝑥𝑏𝑢𝑢 𝐾 𝑡 energy per time)  Mechanical Power Appli liance ance Pow ower er  𝑄 = 𝐺 × 𝑤 T.V. 120 W  F = Force (weight 𝐺 = 𝑛𝑕 g = 9.8 𝑛 𝑡2 ) Computer and Monitor 270 W  v = velocity Washing Machine 425 W  Electrical Power  𝑄 = 𝐽 × 𝑊 Refrigerator 725 W  I = current Dishwasher 1,800 W  V = voltage Dryer 3,400 W  The hoover dam on average produces 4.5×10 4 W per hour. 4

TYPES OF ENERGY Potential Kinetic  Gravitational  Motion  Stored Mechanical  Electrical  Chemical  Radiant  Nuclear  Thermal  Electrical  Sound  Sound 5

GRAVITATIONAL POTENTIAL ENERGY  Energy from position.  𝐹 = 𝑛𝑕ℎ 𝑛  g=9.8 𝑡 2  h=height  m=mass  Examples of gravitational energy: 6

MOTION KINETIC ENERGY  Energy from motion. 2 𝑛𝑤 2  𝐹 = 1  m=mass  V=velocity  Examples of motion energy: 7

ENERGY TRANSFER  Law of conservation of energy  Energy cannot be created or destroyed 8

CHEMICAL POTENTIAL ENERGY  Energy that can be released if a chemical reaction occurs.  Combustion  2C 8 H 18 + 25O 2  16CO 2 + 18H 2 O Δ H=-10,941 𝑙𝐾 𝑛𝑝𝑚  Examples of chemical energy: 9

STORED MECHANICAL POTENTIAL ENERGY  Energy stored in object by tension.  Spring 2 𝑙𝑦 2  𝐹 = 1  K = spring constant  x = distance from at rest position  Stretched rubber band  Examples of stored mechanical energy: 10

NUCLEAR POTENTIAL ENERGY  The energy stored inside the nucleus of an atom.  𝑞𝑛 𝑞 + 𝑜𝑛 𝑜 ≠ 𝑛 𝑜𝑣𝑑𝑚𝑣𝑡  𝐹 = 𝑛𝑑 2  m = mass  c = speed of light 3.00×10 8 𝑛 Fission 𝑡  Examples of nuclear energy  Fission (Breaking atoms apart) 235 𝑉 + 0 1 𝑜 → 141 𝐶𝑏 + 36 92 𝐿𝑠 + 3 0 1 𝑜  92 56 Fusion  releases 3.5x10 -11 J per reaction (2.1×10 13 J per mole)  Fission is what happens in nuclear reactors. Although no pollutant are produced, radio active waste is left over.  Fusion (Joining atoms together)  6D  2 4 He + 2p + 2n  releases 3×10 8 kJ per each gram D  These are the type of reactions that go on in the sun.  In order to get fusion to happen on earth we need to be at high temperatures (10 8 K) 11

ELECTRICAL POTENTIAL OR KINETIC ENERGY  Potential  The energy associated with the attractive force between 2 oppositely charged particles 𝑟 1 𝑟 2  𝐹 = 1 4𝜌𝜁° 𝑠 12  ε˚= vacuum permittivity 8.85 × 10 −12 𝐷2 𝐾∙𝑛  q = charge  r = separation  Kinetic  The energy generated from the flow of electrical change (electrons)  𝐹 = 𝑊𝐽𝑢  V = voltage  I = current  t = time  Examples of electrical energy: 12

RADIANT KINETIC ENERGY  The energy in electromagnetic waves.  𝐹 = ℎ𝜉  h plank’s constant 6.626 ×10 -34 J·s 𝑑  Frequency 𝜉 = 𝜇  c speed of light 3.00×10 8 𝑛 𝑡  λ wavelength  Examples of radiant energy: 13

SOUND KINETIC AND POTENTIAL ENERGY  The energy that is moved through substances with longitudinal waves.  𝐹 = 𝑏 2 𝜍 2𝜌𝑔 (E in this expression is energy density or energy per area)  a = particle acceleration  ρ = air density  f = frequency of sound  Examples of sound energy: 14

THERMAL KINETIC ENERGY  Energy that is caused by heat.  When thermal energy is applied atoms/molecules move faster.  𝐹 = 𝑔 1 2 𝑙𝑈  f = degrees of freedom  k = Boltzmann’s constant 1.381 ×10 -23 𝐾 𝐿  T = temperature T=Cold T=Hot  Examples of thermal energy: 15

TYPES OF ENERGY Potential Kinetic  Gravitational  Motion  Stored Mechanical  Electrical  Chemical  Radiant  Nuclear  Thermal  Electrical  Sound  Sound 16

WORLD ENERGY 2014 Source ce of Energy gy Perce rcent nt Petroleum 32% Natural Gas 24% Coal 30% Renewable 10% Nuclear 4% 17

WORLD ENERGY 2014 Count ntry Energy gy Consumption nsumption Count ntry Energy y Consum nsumpti ption on/p /person son (Quadri adrilli lion on Btu) (MBtu tu) China na 119.3 Qatar tar 1160 United ed Arad Unit ited St States es 98.0 800 Emirat ates es Russia Ru 30.7 Net ether herlands ands 750 India 24.3 Iceland and 687 Japan an 18.9 Kuwai wait 635 Canad ada 14.5 Singap gapore re 633 Brazil 12.8 Bahrai ain 614 German any 12.7 Canada ada 427 Korea, South th 11.1 Norwa way 407 Iran 10.7 Saudi di Arabia 398 United ed St States es 314 (#14 14) 18 http://www.eia.gov/cfapps/ipdbproject/IEDIndex3.cfm?tid=44&pid=44&aid=2

US ENERGY US Sources of Energy 2014 (Quadrillion Btu) Source ce % % % of of World ld US US Energy En gy 2014 14 2014 14 2009 2009 Petroleum 32% 35% 37% Natural Gas 24% 28% 25% Coal 30% 18% 21% Renewable 10% 10% 8% Nuclear 4% 8% 9% 19 http://www.eia.gov/totalenergy/data/monthly/

SOUTHERN CA EDISON Source rce of Energy rgy % Edison 2016 % US 2016 Natural Gas 32% 34% The 2016 Edison numbers Coal 0% 30% recalculate the percentages not using the unspecified Renewable 58% 15% sources of power. Nuclear 10% 20% 20 http://newsroom.edison.com/stories/sce-increases-its-total-renewable-energy-sources

UC REGENTS 21

COMMUNITY CHOICE AGGREGATION 2018 2019 22

ELECTRICITY  Voltage (volt V): A measure of its electrical potential .  Which water tower will have water that comes out at a greater pressure?  What represents voltage? 23

ELECTRICITY  Current (amps A): The rate of charge flow per time .  Which water tower will have water come out at a faster rate?  What represents current?  Types of Current: 24

ELECTRICITY  Resistance (ohms Ω ): The amount of resistance a current will encounter.  Which water tower will have the water encounter more resistance?  What represents resistance? 25

ELECTROMAGNETS  A changing magnetic field induces a electric field.  A changing electric field induces a magnetic field.  Electromagnet: A temporary magnet whose effect is caused by an electric current. 26

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ELECTROMAGNETS 28

 The University of Colorado has computer simulations for different science concepts. Try this one on generators. http://phet.colorado.edu/en/simulation/generator 29

 Transformer: An electrical device by which alternating current of one voltage is changed to another voltage.  The greater the number of coils the greater the voltage. 30