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ENERGY AND POWER

ENERGY AND POWER. THERMODYNAMICS. MOMENTUM. MOMENTUM P = mv FORCE F = ma = mv/t IMPULSE Ft = mv = P (Momentum). MOMENTUM IS ALWAYS CONSERVED There has been the same amount of Momentum in the Universe since the Big Bang. Momentum lost in a collision

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ENERGY AND POWER

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  1. ENERGY AND POWER THERMODYNAMICS

  2. MOMENTUM MOMENTUM P = mv FORCE F = ma = mv/t IMPULSE Ft = mv = P (Momentum) MOMENTUM IS ALWAYS CONSERVED There has been the same amount of Momentum in the Universe since the Big Bang. Momentum lost in a collision Goes into heat, which is increased momentum of the individual Molecules within the heated object.

  3. ENERGY ENERGY IS THE ABILITY TO DO WORK. WORK IS THE APPLICATION OF A FORCE OVER A DISTANCE: IT IS ENERGY USED UP KINETIC ENERGY (energy at work) KE = 1/2 M V2 W = F x d POTENTIAL ENERGY (available for work) TOTAL ENERGY=KE + PE = CONSTANT

  4. FORMS OF ENERGY POTENTIAL KINETIC All the rest are versions of the above HEAT (CAN BE MECHANICAL) CHEMICAL LIGHT ELECTRICAL NUCLEAR

  5. WORK WORK IS FORCE OVER A DISTANCE NEWTON-METRE JOULE

  6. POWER POWER IS A MEASURE OF HOW FAST WORK CAN BE DONE P = W/t POWER IS MEASURED IN WATTS WORK PER UNIT TIME JOULES/SECOND FORCE TIMES SPEED (FxV) NEWTON-METER PER SECOND P = W/t = Fd/t = Fv

  7. CONSERVATION OF ENERGY ENERGY IS MANIFEST IN MANY FORMS, BUT ALTHOUGH WE CAN CONVERT ENERGY FROM ONE FORM TO THE OTHER, IN A CLOSED SYSTEM, THE TOTAL ENERGY REMAINS A CONSTANT. ENERGY CAN NEITHER BE CREATED NOR DESTROYED

  8. ENERGY IF POWER IS STRENGTH, ENERGY IS ENDURANCE ENERGY is POWER X TIME E = Pt = Fdt/t = Fd = WORK UNIT OF ENERGY =WATT-SECOND =JOULE =NEWTON-METER

  9. HEAT TRANSFER CONDUCTION CONVECTION RADIATION EVAPORATION

  10. STEPHAN-BOLTZMANN LAW E(radiation) =a constant x T4 KIRCHHOFF’S LAW: GOOD ABSORBERS ARE ALSO GOOD EMITTERS BLACK BODY = A PERFECT EMITTER

  11. WIEN’S LAW Lamda (max) = C/T The peak wavelength of the emitted radiation is inversely proportional to the absolute temperature

  12. INVERSE SQUARE LAW Radiation decreases by the square of the distance Intensity = Io/d2 1- 100 2- 25 = 1/4 3- 11.1= 1/9 4- 6.25= 1/16 5- 4 = 1/25 6- 2.78 = 1/36 100 * 50 * * * * * 1 3 4 5 6 2

  13. NUCLEAR ENERGY E = MC2 FISSION: BREAKING A NUCLEUS APART FUSION: FORCING TWO NUCEII TOGETHER

  14. HEAT • One calorie is the amount of heat to raise one gram of water, one degree Celsius. • Specific Heat: Each material needs a certain amount of heat to raise its temp one degree; usually less than one calorie. • One calorie is equivalent to 4.19 joules, enough energy to raise one gram of matter 428 metres higher.

  15. THERMAL EXPANSION • Heat causes the atoms or molecules of any material to “jiggle”. • When jiggling they need more room, so the volume increases with temperature (normally). • Water is an exception: with the temp going down between 4 deg and 0 degrees, water will expand, and on freezing will increase volume by 9%. • Ice has a density of 0.92; thus it floats. • The lowest levels of a pond freeze last, if at all.

  16. CHANGES OF STATE • EVAPORATION • CONDENSATION • BOILING – HEAT OF VAPORIZATION 540 CALORIES

  17. CHANGES OF STATE • MELTING • FREEZING – • HEAT OF FUSION 80 CALORIES • SUBLIMATION

  18. THERMODYNAMICS • HEAT FLOWING IS THERMAL ENERGY • WORK CAN PRODUCE HEAT – • HEAT CAN PRODUCE WORK

  19. THERMODYNAMICS FIRST LAW: ENERGY IS CONSTANT E1-E2=HEAT INPUT - WORK DONE (You can’t win) SECOND LAW: HEAT FLOWS FROM HOT TO COOLER (You can’t break even) ENTROPY ALWAYS INCREASES EVERYTHING TENDS TO GET MORE DISORDERED (You can’t get out of the game!) THIRD LAW: AT ABSOLUTE ZERO, ALL MOTION CEASES

  20. THERMODYNAMICS • FIRST LAW: • TOTAL HEAT = CHANGE IN INTERNAL ENERGY + WORK OUTPUT • CHANGE IN ENERGY = HEAT IN – WORK DONE

  21. THERMODYNAMICS • SECOND LAW • HEAT FLOWS FROM HOT TO COOLER • EFFICIENCY IS WORK/HEAT INPUT • PERFECT EFF. = (Thot –Tcold) Thot

  22. ENTROPY • SECOND LAW: • ENTROPY ALWAYS INCREASES • ENTROPY IS A MEASURE OF DISORDER

  23. THERMODYNAMICS • THIRD LAW: • AT ABSOLUTE ZERO ALL ORDER AND MOTION CEASE

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