Conversion from 5 Decameters to Centimeters

Information about the Decameter (dam)

The decametre is ten metres, written dam. It is a valid SI unit formed with the prefix deca, but like the decimetre it is rarely used. The prefix deca is the only SI multiplier whose symbol is two letters, which makes it slightly awkward to write and may have contributed to its neglect.

Spelling varies. Decametre is the international form; dekameter appears in some American texts, and the symbol dkm is occasionally seen in older material, though dam is the form recognised by the BIPM. The similarity between dam and the abbreviation for decimetre has caused confusion, and some standards bodies discourage the unit for that reason alone.

Where it does appear, it is usually in surveying, forestry and agronomy. Field dimensions, plot spacing and tree heights sit conveniently in the range of a few decametres. Some European cadastral records use the unit. It also occurs in specifications for cable and hose supplied in ten-metre lengths.

The derived area unit is more familiar than the length unit. A square decametre is 100 square metres, which is exactly one are. The are is itself little used, but its hundredfold multiple, the hectare, is the standard measure of land area across most of the world. A hectare is 100 ares, or 10,000 square metres, and can equally be described as a square hectometre.

In practice most people express ten metres simply as ten metres, or as 0.01 kilometres when working at larger scales. The decametre is best understood as a formally correct unit that everyday usage has passed over.

The unit does appear in one everyday context without being named. Swimming pool lane lengths, running track segments and the spacing of street lighting are frequently set in multiples of ten metres. Planning documents that lay out plot frontages or building setbacks often work to the same grid. The quantity is useful; it is only the word that has fallen out of use.

Its square has fared better than the length itself. The are, a hundred square metres, is the square decametre under another name, and although the are is now rare its hundredfold the hectare governs land measurement across most of the world. The same pattern shows in the decare of a thousand square metres, which is the standard unit of farmland in Turkey, Greece, Norway and parts of the Balkans and is simply ten ares. So the decametre survives chiefly by inheritance: nobody quotes a field boundary in decametres, but a great deal of the world's land is bought and sold in units built from it.

One decametre equals 10 metres, 1000 centimetres, or 0.01 kilometres. It is about 32.8084 feet.

Information about the Centimeter (cm)

The centimetre is one hundredth of a metre, written cm. Among the metric subdivisions it is the one people reach for most readily in daily life, occupying the range where objects are small enough to hold but too large to measure comfortably in millimetres.

Body measurement is its most common application. Height, waist, chest and inside leg are recorded in centimetres across most of the world, and clothing is sized accordingly. Paediatric growth charts plot height and head circumference in centimetres against age. Rainfall over long periods, snow depth and the dimensions of furniture and luggage are all reported the same way.

The unit had a formal role in science for nearly a century. The centimetre-gram-second system, adopted by the British Association for the Advancement of Science in 1874, took the centimetre as its base unit of length. CGS units such as the erg, the dyne and the gauss were standard in physics until the metre-kilogram-second system displaced them, and SI formally superseded CGS in 1960. Some CGS units persist in astronomy and in parts of electromagnetism.

Volume follows naturally. A cubic centimetre, written cm³ or cc, equals exactly one millilitre. Engine displacement is often quoted in cubic centimetres, particularly for motorcycles, and medical syringes are marked the same way.

Despite its usefulness, the centimetre sits awkwardly in engineering practice. Technical drawings prefer millimetres precisely to avoid mixing units that differ by a factor of ten, since a misplaced decimal point between the two is a plausible and expensive error.

Map scales often make the unit explicit. A 1:25,000 map means one centimetre on the paper represents 25,000 centimetres on the ground, or 250 metres, so four centimetres cover a kilometre. Walkers and orienteers use this relationship constantly, and it is one of the clearer illustrations of why a decimal system is convenient: converting between the two scales requires only moving a decimal point.

Two well-known wavelengths fall in this range and are named by it. Neutral hydrogen radiates at 21 centimetres, a line predicted in 1944 and detected seven years later, and because hydrogen fills the galaxy that single wavelength has mapped the spiral arms of the Milky Way and the rotation curves that first indicated dark matter. Domestic microwave ovens work at 12.2 centimetres, chosen from a band set aside for industrial and medical use rather than for any special resonance with water. In both cases the centimetre is the natural unit because the wave is the size of a hand.

One centimetre equals 10 millimetres or 0.01 metres, and is very close to 0.3937 inches.