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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

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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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

Energy can take many forms

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

Potential + Kinetic = Mechanical

KINETIC ENERGY

Energy of Motion

Law of Conservation of Energy

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

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.

Chemical potential energy  Kinetic energy

• The light energy also produces heatenergy.
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)
The two most common energy conversions are:
• Potentialenergy changing into kinetic energy.
• Kinetic energy changing into potentialenergy.

Thermal Energy

Conduction
• Transfer of heat energy from one solid object to another when they are in direct contact.
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
• 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
• 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.
Electromagnetic waves travel through the emptiness of space.
• They can also pass through many types of matter.
• All warm bodies radiate heat energy in the form of infrared electromagnetic waves.

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

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

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

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