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NS1300 – Emergence of Modern Science Energy and Thermodynamics

NS1300 – Emergence of Modern Science Energy and Thermodynamics. Where does our energy come from, and will there be enough in the future?. History of Energy. How much energy did we need before the bronze age? How much energy did we need before the industrial revolution?

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NS1300 – Emergence of Modern Science Energy and Thermodynamics

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  1. NS1300 – Emergence of Modern ScienceEnergy and Thermodynamics

  2. Where does our energy come from, and will there be enough in the future?

  3. History of Energy • How much energy did we need before the bronze age? • How much energy did we need before the industrial revolution? • How much energy do we need now? • How much energy will we need in the future?

  4. Energy • Mechanical Energy • Thermal Energy • Chemical Energy • Electromagnetic Energy • Entropy

  5. The 1st law of Thermodynamics • The increase in the internal energy of a thermodynamic system is equal to the amount of heat energy added to the system minus the work done by the system on the surroundings. • Heat is a process by which energy is added to a system or lost to a sink. • Energy is lost to a system by doing mechanical work. • Energy is always conserved between a system and its surroundings.

  6. Law of Conservation of Energy • Energy is Neither Created nor Destroyed • Enthalpy: H = U + pV • H is the enthalpy • U is the internal energy • p is the pressure of the system • V is the volume • Entropy: S = k log W • W is the number of microstates corresponding to a given macrostate • K is Boltzmann’s Constant • Open Systems and Closed Systems • The Universe is the Only Closed System in Nature

  7. The 2nd Law of Thermodynamics • In an isolated system, a process can occur only if it increases the total entropy of the system. • Heat cannot spontaneously flow from a material at lower temperature to a material at higher temperature. • It is impossible to convert heat completely into work.

  8. Applications of Entropy • Engineering • Mechanical • Chemical • Electrical • Biology • The Environment

  9. Energy Conversion • Any form of energy can be transformed into any other form • Energy is the Ability to Do Work

  10. Work • Work = Force X Distance (W = Fd) • Simple Machines

  11. Mechanical Energy • Potential Energy • PE = -G(m1m2/R) • Kinetic Energy • E = 1/2mv2

  12. Thermal Energy • Thermal Energy • Heat • Temperature • Calories

  13. Thermodynamics • Thermal Energy • The internal energy of a system associated with kinetic energies of the molecules: • molecular translation, • rotation, and • vibration • electron translation and spin • nuclear spin • and the phase of the system.

  14. Heat and Temperature • Specific Heat • Latent Heat • Molecular Kinetic Energy • Temperature Scales • Fahrenheit • Celsius • Kelvin • Absolute Zero

  15. Flow of Heat • Radiation • Conduction • Convection

  16. Heat Budgets Heat Budget of the Atmosphere and Ocean: QT = QSW + QLW + QS + QL + QV Thermoregulation

  17. Efficiency • Engines • Systems • Organisms

  18. Power • Power = Work / Time (P = W/t)

  19. Power Sources • Solar • Fossil Fuels • Electricity • Batteries

  20. Future Energy Sources • Wind • Geothermal • Nuclear • Biofuels • Hydrogen

  21. Misconceptions About Entropy • Zero Point Energy • Tachyons? • Perpetual motion • Pseudoscience?

  22. Quiz • 1. T or F, energy is the ability to do work. • 2. T or F, any form of energy can be converted to any other form of energy. • 3. Simple machines make work easier, but less efficient. Name a simple machine. • 4. T or F, photons can cause electrons to flow through a circuit. • 5. T or F, zero-point energy is a viable alternative source of energy for the future.

  23. Test Questions • Energy is the capacity to do work. Potential Energy = the potential to do work. Kinetic Energy = the energy of motion (momentum). • Any form of energy can be converted to any other form of energy. All energy can be accounted for in a closed system (in other words, energy is conserved). Entropy describes the total energy of a system and tells us that we cannot get more energy out of a system than we put into it. • W = Fd; Power = W / t; Simple Machines make work easier by changing the distance through which force is applied. • Thermal energy is the internal and external energy of atoms. Heat is the transfer of thermal of energy between atoms. Temperature is a measurement of the kinetic energy of molecules. • Adding heat energy to substances makes their temperature rise (specific heat). To change the state of a substance requires even more heat energy (latent heat). • Heat can be transferred by radiation, conduction, and convection. • Organisms transfer energy through trophic chains. The higher you are on the food chain, the less efficient you are in converting the energy contained in your food into work (activity; yes, thinking is activity).

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