When the figure is not level people cannot know what is meant by width, depth, or height without being told (or without labels), although length is generally still assumed to mean the direction in which the figure is longest..
The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.oal is primarily used as a solid fuel to produce electricity and heat through combustion. World coal consumption was about 7.25 billion tonnes in 2010 (7.99 billion short tons) and is expected to increase 48% to 9.05 billion tonnes (9.98 billion short tons) by 2030.
Coal is called a fossil fuel because it was made from plants that were once alive! Since coal comes from plants, and plants get their energy from the sun, the energy in coal also came from the sun.Th e coal we use today took millions of years to form.n fact, it is burned in power plants to produce more than half of the electricity we use. A stove uses about half a ton of coal a year. A water heater uses about two tons of coal a year. And a refrigerator, thatâs another half-ton a year.