Convert Quarter (US) (qr (US)) to Atomic Mass Unit (u) instantly.
About these units
Quarter (US) (qr (US))
The US quarter equals 25 pounds, serving as a smaller commercial subdivision of the hundredweight. It was used for pricing agricultural goods, livestock feed, and some industrial materials. Its convenience arises from the fact that four quarters make a hundredweight, simplifying scaling between small and medium quantities. Today it is mostly of historical interest, but agricultural economists still encounter it when analyzing archival data.
Atomic Mass Unit (u)
The atomic mass unit (u) is defined as exactly 1/12 the mass of a neutral carbon-12 atom, which makes it approximately 1.66053906660 × 10⁻²⁷ kilograms. This definition allows scientists to express atomic and molecular masses in a convenient, intuitive scale that aligns with the structure of the periodic table. By anchoring the unit to carbon-12, chemists and physicists gained a universal reference point that harmonizes molecular weight, relative isotopic abundance, and mass spectroscopy results. The atomic mass unit effectively normalizes the complexity of atomic masses into whole-number or near-whole-number values for most nuclei. In chemistry, u is indispensable for calculating molar masses, reaction stoichiometry, and isotopic compositions. It is also used across nuclear physics, astrophysics, and biophysics, demonstrating the universality of atomic-scale measurement.