Coal is a combustible black or brownish-black sedimentary rock composed mostly of carbon and hydrocarbons. It is the most abundant fossil fuel on the planet and has been used for centuries as a source of energy. Coal is formed from the remains of ancient plants and trees that were buried and subjected to geologicalpressure and heat over millions of years.
Types of Coal
There are four main types of coal:
Anthracite: This is the highest quality coal, known for its high carbon content and low impurities. It is hard, black, and has a high energydensity.
Bituminous: Bituminous coal is a dense, black coal that is often used for heating and electricity generation. It has a higher energy content than lignite and sub-bituminous coal.
Sub-bituminous: This type of coal is black in color and has a higher moisture content than bituminous coal. It is commonly used for electricity generation.
Formation of Coal
Coal is formed from the remains of plants and trees that lived millions of years ago. When these organic materials died, they accumulated in swamps and peat bogs. Over time, the accumulated plantmatter was buried under layers of sediment, and as more and more sediment accumulated, the heat and pressure from the overlying layers caused the plantmaterial to undergo chemical and physicalchanges, eventually forming coal.
Uses of Coal
Coal has been used for various purposes, including:
The student demonstrates an understanding of motions, forces, their characteristics, relationships, and effects by explaining that different kinds of materials respond to electric and magnetic forces (i.e., conductors, insulators, magnetic and non-magnetic materials).