Sustainable Energy - Without the Hot Air
4.2. Wind II http://www.ck12.org 4.2 Wind II The physics of wind power To estimate the energy in wind, let’s imagine holding up ...
http://www.ck12.org Chapter 4. Technical Chapters The kinetic energy of this piece of air is 1 2 mv^2 = 1 2 ρAvtv^2 = 1 2 ρAtv^3 ...
4.2. Wind II http://www.ck12.org Figure B.2:Flow of air past a windmill. The air is slowed down and splayed out by the windmill. ...
http://www.ck12.org Chapter 4. Technical Chapters Figure B.3:The Brooklyn windmill above Wellington, New Zealand, with people pr ...
4.2. Wind II http://www.ck12.org B.6 shows the mean winter and summer windspeeds in eight more locations around Britain. I fear ...
http://www.ck12.org Chapter 4. Technical Chapters wherez 0 is a parameter called the roughness length, andvrefis the speed at a ...
4.2. Wind II http://www.ck12.org generate in optimal conditions. Usually, wind turbines are designed to start running at wind sp ...
http://www.ck12.org Chapter 4. Technical Chapters Figure B.10:A 5.5-m diameter Iskra 5 kW turbine [www.iskrawind.com] having its ...
4.3 Planes II http://www.ck12.org Contents 4.3 Planes II What we need to do is to look at how you make air travel more energy ef ...
http://www.ck12.org Chapter 4. Technical Chapters Figure C.2:A plane encounters a stationary tube of air. Once the plane has pas ...
4.3. Planes II http://www.ck12.org Figure C.4:Air flow behind a plane. Photo by NASA Langley Research Center. The sausage’s mass ...
http://www.ck12.org Chapter 4. Technical Chapters Plift= kinetic energy of sausage time (C. 7 ) = 1 t 1 2 msausageu^2 (C. 8 ) = ...
4.3. Planes II http://www.ck12.org Figure C.5: The force required to keep a plane moving, as a function of its speedv, is the su ...
http://www.ck12.org Chapter 4. Technical Chapters TABLE4.8: Bird 747 Albatross Designer Boeing natural selection Mass (fully-lad ...
4.3. Planes II http://www.ck12.org Interesting! Independent of the density of the fluid through which the plane flies, the requi ...
http://www.ck12.org Chapter 4. Technical Chapters transport cost= 1 ε force mass (C. 24 ) = 1 ε (cdfA) (^12) mg m (C. 25 ) = (cd ...
4.3. Planes II http://www.ck12.org This gross transport cost is the energy cost of moving weight around,including the weight of ...
http://www.ck12.org Chapter 4. Technical Chapters Figure C.11:Boeing 737-700: 30 kWh per 100 passenger-km. Photograph © Tom Coll ...
4.3. Planes II http://www.ck12.org This figure is again close to the true answer: the nonstop flight record for a 747 (set on Ma ...
http://www.ck12.org Chapter 4. Technical Chapters 0.4 kWh per ton-km bench-mark. If a plane uses less than 0.4 kWh per ton-km, w ...
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