11.3 Energy Flow in Systems

Chapter 11 Objectives  Give an example of a process and the efficiency of a process.  Calculate the efficiency of a mechanical system from energy and work.  Give examples applying the concept of efficiency to technological, natural and biological systems.  Calculate power in technological, natural, and biological systems.  Evaluate power requirements from considerations of force, mass, speed, and energy.  Sketch an energy flow diagram of a technological, natural, or biological system.

Chapter 11 Vocabulary  carnivore  cycle  decomposer  ecosystem  efficiency  energy conversions  energy flow  food calorie  food chain  food web  herbivore  horsepower  irreversible  power  power transmission  producer  reversible  steady state  watt

Inv Energy Flow in Systems Investigation Key Question: Where did the energy go?

11.3 Energy flow in systems Energy flows almost always involve energy conversions. To understanding an energy flow: 1.Write down the forms that the energy takes. 2.Diagram the flow of energy from start to finish for all the important processes that take place in the system. 3.Try to estimate how much energy is involved and what are the efficiencies of each energy conversion.

11.3 Energy flow in systems  A pendulum is a system in which a mass swings back and forth on a string.  There are 3 chief forms of energy: potential energy, kinetic energy, and heat loss from friction.

11.3 Energy flow in human technology The energy flow in technology can usually be broken down into four types of processes: 1.Storage ex. batteries, springs, height, pressure 2.Conversion ex. a pump converting mechanical energy to fluid energy  Transmission ex. through wires, tubes, gears, levers  Output ex. heat, light, electricity

11.3 Energy flow  The energy flow diagram for a rechargeable electric drill shows losses to heat or friction at each step.

11.3 Energy flow in natural systems  The energy flows in technology tend to start and stop.  Many of the energy flows in nature occur in cycles.  Water is a good example.

11.3 Energy flow in natural systems  A food chain is a series of processes through which energy and nutrients are transferred between living things.  A food chain is like one strand in a food web.  A food web connects all the producers and consumers of energy in an ecosystem.

11.3 Energy flow in natural systems  The energy pyramid is a good way to show how energy moves through an ecosystem.

 The energy and power in tides is enormous.  The power that moves the oceans and creates tides comes from the total potential and kinetic energy of the Earth-Moon system.  Many experimental projects have been built to harness the power of tides.  Like hydroelectric power, energy from tides creates no pollution, nor does it use up fossil fuels such as petroleum or coal. Energy from Ocean Tides

Business Models Many business models mimic these natural systems Cradle to Grave model Cradle to Cradle model Patagonia

Group Project  Energy Systems Project  Media: PowerPoint presentation  Topic: Energy Systems  Must include:  Diagram of the system  Explanation of energy losses  Efficiency  Heat  Friction  May not include:  Any example discussed in class or included in the presentation  Bonus Points if it is a closed loop system (i.e. “Cradle-Grave-Rebirth”)

Group Project  Rubric:  80% - PowerPoint file  Late submissions will not be accepted for any reason  20% - Group Presentation  Absent members automatically lose this portion  No exceptions  No reschedules allowed