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 flerovium Isotopes of flerovium Flerovium (Fl) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was Fl in 1999 (or possibly 1998). Flerovium has seven known isotopes, and possibly 2 nuclear isomers. The longest-lived isotope is Fl with a half-life of 1.9 seconds, but the unconfirmed Fl may have a longer half-life of 19 seconds. The below table contains various combinations of targets and projectiles which could be used to form compound nuclei with an atomic number of 114. "This section deals