Chapter 1  Energy and Power
Download
1 / 8

Chapter 1 Energy and Power - PowerPoint PPT Presentation


  • 76 Views
  • Uploaded on

Chapter 1 Energy and Power. Energy - the ability to do work; anything that can be turned into heat. Several forms: Kinetic KE = 1/2 mv 2 Heat is special form Potential (stored) Can be mechanical (spring), electro-chemical (battery), or electronic (energy stored in excited atoms)

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Chapter 1 Energy and Power' - prescott-pollard


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Chapter 1 Energy and Power

  • Energy - the ability to do work; anything that can be turned into heat.

  • Several forms:

    • Kinetic KE = 1/2 mv2

      • Heat is special form

    • Potential (stored)

      • Can be mechanical (spring), electro-chemical (battery), or electronic (energy stored in excited atoms)

      • Gravity is special case PE = mgh

    • Chemical bonds

    • “Light”

    • Mass (Einstein’s famous E = mc2)


Work, Energy, Power, and their units

  • (Physics) Work = Force x distance

  • Work and energy have same units

    • Joules in metric

    • Foot-pounds in English (seldom used)

    • 1 Calorie = 1000 calories

  • Power is the time rate of doing work or the time rate of gaining or losing energy

  • Units of Power = Joule/sec = Watt

  • So kWh is a unit of energy

  • Energy Content Table


Alternative Energy: Gasoline, batteries, and fuel cells

  • Gasoline is (relatively) cheap, but has problems…

    • Unreliable and price may go higher

    • Efficiency, pollution and greenhouse gas production

  • So what’s wrong with batteries?

    • Heavy and bulky

    • Low energy per gram compared to gasoline

    • Expensive to replace (especially ones with most energy/volume)

  • Hybrids?

    • Still problems with batteries

    • Best with limited use of batteries (they last longer)


But the electric cars are coming!

The Tesla Roadster

The Chevy Volt


What’s all the hype about hydrogen?

  • Not mined; made from water using hydrolysis

  • Fuel cell creates water and electricity

  • Lower energy/volume than gasoline

    • Even when compressed (1/6 as much) or liquified (1/3 as much)

  • Made from methane, but produces CO2

  • BUT, hydrogen fuel cells produce no pollution, not even CO2, so there may be conditions under which their use is justified. Just don’t expect a hydrogen car any time soon.


Have an eye on those tables!

  • Page 1-12 Notice coal and natural gas vs. gasoline

  • Page 1-16 Examples of energy units

  • Page 1-18 Examples of power units

  • These are really good sources of test questions!


Solar Power

  • About 1 kW shines on 1 m2

  • About 1 GW shines on 1 km2

  • Take solar cell efficiency into account…

    • 1 m2 gives 150-400 W of electricity

    • 1 km2 gives 150-400 MW of electricity

  • Use hydrogen storage for night energy?

  • Solar cells are expensive and fragile


Kinetic Energy Killed the Dinosaurs

Recall that KE = 1/2 mv2

  • Fragment G:

    • 1 km diameter

    • 2000 kg/m3

    • 60 km/s

  • 1000 Giga-tons of TNT


ad