Weight on bit Weight on bit Weight on bit (WOB), as expressed in the oil industry, is the amount of downward force exerted on the drill bit and is normally measured in thousands of pounds. Weight on bit is provided by drill collars, which are thick-walled tubular pieces machined from solid bars of steel, usually plain carbon steel but sometimes of nonmagnetic nickel-copper alloy or other nonmagnetic premium alloys. Gravity acts on the large mass of the collars to provide the downward force needed for the bits to efficiently break rock. To accurately control the amount of force applied to the bit, the
Isotopes of nihonium Isotopes of nihonium Nihonium (Nh) is a synthetic element. Being synthetic, a standard atomic weight cannot be given and like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was Nh as a decay product of Mc in 2003. The first isotope to be directly synthesized was Nh in 2004. There are 6 known radioisotopes from Nh to Nh, along with the unconfirmed Nh. The longest-lived isotope is Nh with a half-life of 8 seconds. Super-heavy elements such as nihonium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. Whereas most