MAR 110 Lecture #2 Energy Sources What is the cause of

5 September 2007 Lecture 2 Outline – Energy

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MAR 110 Lecture #2 Energy Sources

What is the cause of Earth and Ocean Hazards ?

...slowly-accumulated ENERGY isreleased suddenly or concentrated in a small

region!

Energy?Energy is the capacity to do work

Work?…….to do Work a force acts over a distance

Figure 2.1 How can energy do work? Energy is required to move something with force – that do work . For example, the energy of the moving water causes the wheel to turn. (UWaC)


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Energy = The capacity of any system to do work.

Chemical EnergyEnergy stored in molecular bonds.

Thermal EnergyEnergy Related to Heat.

What is Energy & it’s Forms?

Mechanical EnergyEnergy Related to Motion and Position

Mechanical EnergyEnergy Related to Motion and Position.

Kinetic EnergyEnergy any system possesses by virtue of its motion.

Potential EnergyEnergy any system possesses by virtue of its position.

What is Energy & it’s Forms?


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Energy Can Easily Move Back and Forth

Between Different Forms

Figure 2.2 What is potential energy? These are examples of various forms of potential or “stored’ energy. Water behind a dam can be used to generate electricity; wood can be burned to produce heat; food is converted into energy for body movement. (UWaC)


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Ocean Waves Contain Both Kinetic and Potential Energy!

One Form of Energy: Mechanical Energy

Mechanical Energy builds Ocean WavesEarthquakes do work on the sea floor & create tsunami waves

Winds do work on the sea surface & create ocean waves

Concentration of energy can have disastrous consequences:

Tsunami waves are “small” and virtually unseen at sea!……….Deep water allows the energy to spread out across

a large depth

At the coast, shallow water concentrates the energyin the tsunami waves into a Destructive Force.

. . . This is not unlike using a magnifying glass to start a fire . . . or fry ants!!


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Earth Material has – MECHANICAL ENERGY (ME)

Potential Energy (PE) by virtue of its position; (For example, wave height above sea level)

Kinetic Energy (KE) by virtue of its motionME= PE + KE

Heat Energy is another energy form

Energy converts from one form to another(For example. Heat Energy causes molten rock to rise (ME)

Earth & Ocean Hazards are Energized by Heat1. Earth heat (internal)2. Solar heat (external)

(Note: external energy far greater than internal energy)

Other Examples of Work

Earthquakes are Earth Movement

Undersea Earth Movement generates Tsunami Waves

Tsunami Waves carry energy long distances

Tsunami Wave Energy causes Destruction at the Coast


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Figure 2.3 Internal Energy Source-Radioactive Decay Radioactive decay deep inside the earth produces geothermal energy (heat) as well as create convection currents within the mantle that drive plate tectonics. (?)

Figure 2.1 Tsunami Generation The two main causes of tsunamis are underwater earthquakes/faulting (left) and landslides (right). Both have the capacity to displace the large volume of water necessary to generate a tsunami. (?NG?)


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Figure 2.4 External Energy Source-the Sun The sun is the source of nearly all the energy used on earth, mostly in the form of heat which drives both oceanic and atmospheric processes. (UWaC)


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Figure 2.5 Solar Energy and the Hydrologic Cycle Partition of solar energy showing the relative amounts reflected, absorbed and radiated energy in the earth-ocean-atmosphere system. (?)

Figure 2.6 Hurricane Structure Warm moist air enters at the bottom of a hurricane and spirals upward through convection. As the air moves upward it cools and releases moisture, strengthening the storm. (?)

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MAR 110 Lecture #2 Energy Sources What is the cause of