10 most difficult measures riddles

President Gerald Ford signed the Metric Conversion Act in1975. It declared the metric system "the preferred system of weights and measures for United States trade and commerce", but permitted the use of United States customary units in all activities. The metrification board was abolished in 1982 by President Ronald Reagan.

An anemometer is a device used for measuring the speed of wind, and is also a common weather station instrument. The term is derived from the Greek word anemos, which means wind, and is used to describe any wind speed measurement instrument used in meteorology.

The yard is an English unit of length, in both the British imperial and US customary systems of measurement, that comprises 3 feet or 36 inches. It is by international agreement in 1959 standardized as exactly 0.9144 meters.

One yard is 0,91 m; one foot is 0,3 m; ell was typically 60-70 cm.

The moment magnitude scale (MMS; denoted as Mw or M) is one of many seismic magnitude scales used to measure the size of earthquakes

In 1929, the international nautical mile was defined by the First International Extraordinary Hydrographic Conference in Monaco as precisely 1,852 meters. The United States nautical mile was defined as 6,080.20 feet (1,853.24 m) based in the Mendenhall Order foot of 1893. It was abandoned in favour of the international nautical mile in 1954. The Imperial nautical mile, often called an Admiralty mile, was defined by its relation to the Admiralty knot, and was abandoned in 1970.

The sverdrup (symbol: Sv) is a non-SI unit of volume transport. It is used almost exclusively in oceanography to measure the volumetric rate of transport of ocean currents. It is named after Harald Sverdrup. It is equivalent to 1 million cubic metres per second (264,000,000 USgal/s).The entire global input of fresh water from rivers to the ocean is equal to about 1.2 sverdrup.

The knot is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h. The ISO standard symbol for the knot is kn. Worldwide, the knot is used in meteorology, and in maritime and air navigation—for example, a vessel travelling at 1 knot along a meridian travels approximately one minute of geographic latitude in one hour.

Nautical mile equals 1852 meters (in some countries slightly different values are used), land mile (statute mile) in the U.S. is 1609 meters, verst was approx 1077 meters.

The parsec (symbol: pc) is a unit of length used to measure large distances to astronomical objects outside the Solar System. One parsec is equal to about 3.26 light-years (30 trillion km or 19 trillion miles) in length. The nearest star, Proxima Centauri, is about 1.3 parsecs (4.2 light-years) from the Sun.