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
Atomic mass more significant figures than atomic weights. Standard atomic weight is related to atomic mass by the abundance ranking of isotopes for each element. It is usually "about" the same value as the atomic mass of the most abundant isotope, other than what looks like (but is not actually) a rounding difference. The atomic mass of atoms, ions, or atomic nuclei is slightly less than the sum of the masses of their constituent protons, neutrons, and electrons, due to binding energy mass loss (as per "E"="mc"). Relative "isotopic" mass (a property of a single atom) is not to be confused with