Chapter 1 Energy and Power

1 / 8

Chapter 1 Energy and Power - PowerPoint PPT Presentation

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)

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

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

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 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