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How much energy is one Joule? Not much!

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How much energy is one Joule? Not much! - PowerPoint PPT Presentation


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What is energy?. Energy is the ability to do work The unit of energy is the Joule, named after James Prescott Joule This is also the unit of work, since energy and work are manifestations of the same thing. http://dspt.club.fr/PortraitJoule.jpg. How much energy is one Joule?

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Presentation Transcript
slide2

What is energy?

  • Energy is the ability to do work
  • The unit of energy is the Joule, named after James Prescott Joule
    • This is also the unit of work, since energy and work are manifestations of the same thing

http://dspt.club.fr/PortraitJoule.jpg

  • How much energy is one Joule?
  • Not much!
    • One Joule is the amount of energy it takes to lift a small apple to a height of one meter on the earth
    • Often we talk about kiloJoules, thousands of Joules
slide3

Energy can take many forms

  • Mechanical-Kinetic and Potential
  • Light
  • Electrical
  • Nuclear
  • Heat
  • Chemical
chemical energy
Chemical Energy
  • Type of potential energy
mechanical energy
Mechanical Energy

Potential + Kinetic = Mechanical

slide15
KINETIC ENERGY

Energy of Motion

law of conservation of energy
Law of Conservation of Energy

Energy cannot be created nor destroyed but can converted into another form of energy.

slide17

Energy is conserved

  • It may change forms but you cannot lose energy
  • A falling apple illustrates the relationship between potential and kinetic energy
    • You can convert it to a form that does not do work such as heat lost as friction

Kinetic energy increases as it falls

Potential energy decreases as it falls

food is a type of fuel
Food is a type of fuel.

Chemical potential energy  Kinetic energy

slide25
Electrical energy may power a light bulb and be converted to lightenergy.
  • The light energy also produces heatenergy.
slide27
Einstein\'s equation shows this relationship.
  • E = Energy (Joules)
  • m = mass (kg)
  • c = speed of light (300,000 km/s or 3 x 108 m/s)
slide28
The two most common energy conversions are:
  • Potentialenergy changing into kinetic energy.
  • Kinetic energy changing into potentialenergy.
conduction
Conduction
  • Transfer of heat energy from one solid object to another when they are in direct contact.
slide34
Metals and other materials that readily (easily) transfer heat energy through themselves are called conductors.
  • Materials that transfer heat energy poorly are called insulators.
convection
Convection
  • Process of heat transfer in fluids (liquids and gases) by means of rising and falling currents.
  • When a region of liquid or gas absorbs heat energy, its molecules move faster, and the distance between them increases.
  • The region of fluid expands as a result and becomes less dense than its surroundings.
radiation
Radiation
  • Transfer of heat energy in the form of electromagnetic waves
  • The same kinds of energy waves transfer heat and light energy from the Sun as it radiates energy to Earth.
slide40
Electromagnetic waves travel through the emptiness of space.
  • They can also pass through many types of matter.
slide41
Infrared electromagnetic waves are sensed by nerves in the skin as heat.
  • All warm bodies radiate heat energy in the form of infrared electromagnetic waves.
slide44

In which case would the object have

more potential energy?

OR

A bird in your hand, 1 m above theground

The same bird on the limb of a tree, 5 m above the ground

slide45

In which case would the object have

more potential energy?

OR

A tennis ball, sitting on a shelf 2 m above the ground

A softball, sitting on a shelf 2 m above the ground

slide46

Which object has greater kinetic energy?,

OR

A bowling ball, rolling at a speed of 2 m/s

A beach ball, rolling at a speed of 2 m/s

slide47

Which object has greater kinetic energy?,

OR

A golf ball, flying through the air at a speed of 10 m/s

A golf ball, flying through the air at a speed of 15 m/s

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