Weight on bit downhole MWD sensors can measure weight-on-bit more accurately and transmit the data to the surface. 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
Isotopes of roentgenium Isotopes of roentgenium Roentgenium (Rg) 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 Rg in 1994, which is also the only directly synthesized isotope; all others are decay products of nihonium, moscovium, and tennessine, and possibly copernicium, flerovium, and livermorium. There are 7 known radioisotopes from Rg to Rg. The longest-lived isotope is Rg with a half-life of 2.1 minutes, although the unconfirmed Rg and Rg may have a longer half-life of about 5.1 minutes and 10.7 minutes respectively.