Metrication in the United States There are no U.S. customary units for electric current, potential difference, or charge since these concepts were developed after the international adoption of metric in science. The metric units ampere, volt, ohm and coulomb are the only units used. The SI term hertz has replaced the term "cycles per second" as a unit of frequency. Energy is often measured in watt hours, BTUs, therms or calories rather than the SI joule. Residential and commercial electrical energy use is metered and billed in kilowatt hours, kW·h, as in most metric countries. Force measurements regularly use the pound instead of the SI
Bubnoff unit Bubnoff unit The Bubnoff unit (abbreviated B) is a unit of speed equal to 1 m / 10 a. In other words, 1 B is equal to 1 meter in 1,000,000 years, 1 millimeter in 1,000 years, or one micrometer per year. It was defined in 1969. The Bubnoff unit is employed in geology to measure rates of lowering of earth surfaces due to erosion and is named after the Russian (German-Baltic) geologist Serge von Bubnoff (1888–1957). An erosion speed of 1 B also means that 1 m³ of earth is being removed from an area of 1 km² in