ENERGY

Energy

The current patterns of energy use raise many important environmental issues.

At present much of the developed world, which is formed on technology, relies heavily on non renewable resources

It is estimated that developed countries which represent about 1/3 of the world population account for 2/3 of the world’s energy consumption.

Energy cont’d

The many problems experienced with such a high energy consumption are:

1. Impact on habitat and environment due to extraction eg coal or uranium mining

2. Energy consumption created by the processing of raw materials

3. The enhanced greenhouse effect caused by the use of fossil fuels and non renewable.

The emissions from the combustion of fossil fuels are considered the largest contributor to the enhanced greenhouse effect.

What is energy

Energy is defined as an object or group of objects’ capacity to perform work.

When energy is transferred from an object or system it can perform useful work, work = the amount of energy transferred.

What are the forms of energy? Energy can be mechanical, chemical, heat, electrical, nuclear

and light. Energy can be classified as either kinetic energy (KE) or

potential energy (PE) Kinetic energy is linked with the objects speed or

motion Potential energy is associated with the object’s

position eg height and refers to the stored energy that can be released to perform work.

Example

Kinetic energy is energy in one of its active forms. Potential energy refers to systems or materials that have the potential to release kinetic energy.

Heat and Temperature

Heat and thermal energy plays an important role in nearly all energy transformations.

The molecules of all objects are in motion; they have kinetic energy.

Temperature is a measure of average kinetic energy of the molecules contained within a molecule.

For molecules to increase their kinetic energy and therefore their temperature an injection or transfer of energy must have occurred.

The energy transferred is thermal energy (heat)

Heat and Temperature cont’d

The terms heat and temperature are NOT identical.

Example: Two objects of different temperature are in contact, thermal energy will transfer from the hotter to the cooler until they reach an equilibrium.

This transfer if defined as heat.

Heat and Temperature cont’d Thermal energy is required to change

states of matter. The additional heat increases kinetic

energy of each molecule breaking the bonds that would hold them together.

Thermal

energy increase

Molecules increase

kinetic

energy

and vibration

Temperatu

re will

increase or

Change of state will

occur

Chemical Energy

Is a form of potential energy that is due to the relative positions of the atoms and their electrons in the molecules that make up the substance.

The stored energy can be converted into other forms of energy by combustion.

Combustion is the reaction that occurs between the substance and oxygen, resulting in the release of chemical energy as the bonds are broken.

Energy resources.

Fuels contain chemical potential energy that is released when combusted or oxidised.

Reactions that release heat are called exothermic reactions.

Reactions that take up heat are endothermic reactions

REFERENCES

Issues of sustainability, vaee 2nd ed 2001, pg 4-5, Geoff Duke

http://apesnature.homestead.com/chapter3.html

http://www.mr-harris.co.uk/year11/year11units/C2.html

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