This table contains numbers that are occasionally quoted, sometimes in old-fashioned units, sometimes in metric units. When given in metric units, some of these are nicer round numbers, than in old-fashioned units.
| Quantity | Value in metric units | Value in old-fashioned units |
|---|---|---|
| Speed of lighta | 300 000 km/s | 186 000 mi/s |
| Speed of sound | 330 m/s | 1090 ft/s |
| Acceleration due to Earth’s gravity | 10 m/s2 | 32 ft/s2 |
| Distance between Earth and Sun | 150 000 000 km | 93 000 000 mi |
| Distance between Earth and Moon | 385 000 km | 240 000 mi |
| Circumference of Earthb | 40 000 km | 25 000 mi |
| Geostationary satellite altitudec | 36 000 km | 22 000 mi |
| Freezing point of water | 0 °C | 32 °F |
| Standard human body temperature | 37 °C | 98.6 °F |
| Boiling point of water | 100 °C | 212 °F |
| Atmospheric pressure | 100 kPa | 30 in |
| Density of water | 1 g/mL or 1 kg/L 1 g/cm3 or 1000 kg/m3 or 1 t/m3 |
8.35 lb/gal 0.58 oz/in3 |
| Height of Mount Everest | 8850 m | 29 035 ft |
| Length of marathon footraced | 42.195 km | 26 mi 385 yd |
| World long jump recorde | 8.95 m | 29 ft 4.5 in |
Notes
- The speed of light is exactly 299 792 458 m/s (or 299 792.458 km/s), as specified in the current definition of the metre, established by the 17th General Conference on Weights and Measures in 1983.
- When the metric system was created in the 1790s, the metre was originally specified as 1/10 000 000 of the distance between the Equator and the North Pole, so the Earth’s (polar) circumference was exactly 40 000 000 m (or 40 000 km). The metre has been redefined several times, most recently in terms of the second (i.e., the unit of time) and a defined value for the speed of light (note a). But the Earth’s circumference is still remarkably close to 40 000 km.
- The geostationary satellite altitude is the distance above the earth’s surface, whereas the earth-sun and earth-moon distances are between the centers of the bodies.
- The first marathon race was an even metric 40 km, run during the first Modern Olympics, Athens 1896. The distance fluctuated in subsequent years, until it was standardized in 1924 at 42.195 km, the length first run during the 1908 Olympics in London. This is not an even distance in either kilometres or miles.
- The current long jump record is 8.95 m by Mike Powell, Tokyo 1991. Previous record was 8.90 m by Bob Beamon, Mexico City 1968. Measurements of long jumps, discus throws, etc. and bar heights for high jumps, pole vaults, etc. are always whole numbers of centimetres, although they are often translated to approximate feet/inch equivalents for US audiences.
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