ENERGY UNITS. 1 cal J 1 ev J 1 btu 1055 J 1 kw h J. Your body gets 8,000 J (1900cal=1.9kcal) of energy from eating a

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1 ENERGY 1

2 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 J 1 ev J 1 btu 1055 J 1 kw h J Your body gets 8,000 J (1900cal=1.9kcal) of energy from eating a peanut. 60 J of energy are needed per second to keep a 60 W bulb lit 1 gallon of gas produces J of energy or enough energy to light a 60 W bulb for 25 days. 2

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

4 POWER Power (watt J energy per time) s Mechanical Power P = F v F = Force (weight F = mg g=9.8 m ) s 2 v = velocity Electrical Power P = I V I = current V = voltage Appliance T.V. Computer and Monitor Washing Machine Refrigerator Dishwasher Dryer Power 120 W 270 W 425 W 725 W 1800 W 3400 W The hoover dam on average produces W per hour. 4

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

6 GRAVITATIONAL POTENTIAL ENERGY Energy from position. E = mgh g=9.8 m s 2 h=height m=mass Examples of gravitational energy: 6

7 MOTION KINETIC ENERGY Energy from motion. E = 1 2 mv 2 m=mass V=velocity Examples of motion energy: 7

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

9 CHEMICAL POTENTIAL ENERGY Energy that can be released if a chemical reaction occurs. Combustion 2C 8 H O 2 16CO H 2 O Examples of chemical energy: ΔH=-10,941 kj mol 9

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

11 NUCLEAR POTENTIAL ENERGY The energy stored inside the nucleus of an atom. pm p + nm n m nuclus E = mc 2 m = mass c = speed of light m s Fission Examples of nuclear energy Fission (Breaking atoms apart) 235 U n Ba Kr n 92 releases 3.5x10-11 J per reaction ( J per mole) Fission is what happens in nuclear reactors. Although pollutant are produced, radio active waste is left over. Fusion (Joining atoms together) 6D 2 4 He + 2p + 2n releases 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) Fusion no 11

12 ELECTRICAL POTENTIAL OR KINETIC ENERGY Potential The energy associated with the attractive force between 2 oppositely charged particles E = 1 q 1 q 2 4πε r 12 ε = vacuum permittivity C 2 q = charge r = separation Kinetic The energy generated from the flow of electrical change (electrons) E = VIt V = voltage I = current t = time Examples of electrical energy: J m 12

13 RADIANT KINETIC ENERGY The energy in electromagnetic waves. E = hν h plank s constant J s Frequency ν = c λ c speed of light m s λ wavelength Examples of radiant energy: 13

14 SOUND KINETIC AND POTENTIAL ENERGY The energy that is moved through substances with longitudinal waves. E = a2 ρ 2πf (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

15 THERMAL KINETIC ENERGY Energy that is caused by heat. When thermal energy is applied atoms/molecules move faster. E = f 1 2 kt f = degrees of freedom k = Boltzmann s constant J K T = temperature T=Cold T=Hot Examples of thermal energy: 15

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

17 WORLD ENERGY 2014 Source of Energy Percent Petroleum 32% Natural Gas 24% Coal 30% Renewable 10% Nuclear 4% 17

18 WORLD ENERGY 2014 Country Energy Consumption (Quadrillion Btu) China United States 98.0 Russia 30.7 India 24.3 Japan 18.9 Canada 14.5 Brazil 12.8 Germany 12.7 Korea, South 11.1 Iran 10.7 Country Energy Consumption/person (MBtu) Qatar 1160 United Arad Emirates 800 Netherlands 750 Iceland 687 Kuwait 635 Singapore 633 Bahrain 614 Canada 427 Norway 407 Saudi Arabia 398 United States (#14)

19 US ENERGY US Sources of Energy 2014 (Quadrillion Btu) Source of Energy % World 2014 % US 2014 % US 2009 Petroleum 32% 35% 37% Natural Gas 24% 28% 25% Coal 30% 18% 21% Renewable 10% 10% 8% Nuclear 4% 8% 9% 19

20 SOUTHERN CA EDISON Source of Energy % Edison 2016 % US 2016 Natural Gas 36% 34% Coal 0% 30% Renewable 64% 15% Nuclear 0% 20% The 2016 Edison numbers recalculate the percentages not using the unspecified sources of power. 20

21 COMMUNIT Y CHOICE AGGREGATION The 2016 Edison numbers recalculate the percentages not using the unspecified sources of power. 21

22 ELECTRICIT Y 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? 22

23 ELECTRICIT Y 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: 23

24 ELECTRICIT Y Resistance (ohms Ω): The amount of resistance a current will encounter. Which water tower will have the water encounter more resistance? What represents resistance? 24

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. 25

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27 ELECTROMAGNETS 27

28 The University of Colorado has computer simulations for different science concepts. Try this one on generators. 28

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. 29