NS1300 – Emergence of Modern Science Energy and Thermodynamics.

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Where does our energy come from, and will there be enough in

the future?

Chapter 3 – Energy

• Mechanical Energy

• Thermal Energy

• Chemical Energy

• Electromagnetic Energy

• Entropy

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

Energy Conversion

• Any form of energy can be transformed into any other form

• Energy is the Ability to Do Work

Work

• Work = Force X Distance (W = Fd)

• Simple Machines

Mechanical Energy

• Potential Energy

– PE = -G(m1m2/R)

• Kinetic Energy

– E = 1/2mv2

Thermal Energy

• Thermal Energy

• Heat

• Temperature

• Calories

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.

Heat and Temperature

• Specific Heat

• Latent Heat

• Molecular Kinetic Energy

• Temperature Scales– Fahrenheit– Celsius– Kelvin

• Absolute Zero

Flow of Heat

• Radiation

• Conduction

• Convection

Heat Budgets

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

Thermoregulation

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.

Efficiency

• Engines

• Systems

• Organisms

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.

Applications of Entropy

• Engineering– Mechanical– Chemical– Electrical

• Biology

• The Environment

Misconceptions About Entropy

• Perpetual Motion

• Free Point Energy

• Complexity

Chemical Energy

• Oxidation – Reduction

– Photosynthesis– Respiration– Burning– Rusting

Trophic Levels• Producers– Photosynthesis– Chemosynthesis

• Consumers– Grazers– Predators– Parasites

• Decomposers– Saprophytes

Electromagnetic Energy

•E = mc2

The Photon

• Particle – Wave Duality

• Photoelectric Effect

• Induction

Power

• Power = Work / Time (P = W/t)

Power Sources

• Solar

• Fossil Fuels

• Electricity

• Batteries

Future Energy Sources

• Wind

• Geothermal

• Nuclear

• Biofuels

• Hydrogen

Zero Point Energy – An Alternative Energy Resource?

• Zero Point Energy

• Tachyons?

• Zero Point Energy Generators?

• Pseudoscience?

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.