Environmental radioactivity g) to that of the soil water (Bq ml). If the radioactivity is tightly bonded to by the minerals in the soil then less radioactivity can be absorbed by crops and grass growing in the soil. One dramatic source of man-made radioactivity is a nuclear weapons test. The glassy trinitite formed by the first atom bomb contains radioisotopes formed by neutron activation and nuclear fission. In addition some natural radioisotopes are present. A recent paper reports the levels of long-lived radioisotopes in the trinitite. The trinitite was formed from feldspar and quartz which were melted by the heat. Two samples
Geometrized unit system have the geometric dimension of "length". Physical quantities such as angular momentum which can be identified with the magnitude of a bivector have the geometric dimension of "area". Here is a table collecting some important physical quantities according to their dimensions in geometrized units. They are listed together with the appropriate conversion factor for SI units. This table can be augmented to include temperature, as indicated above, as well as further derived physical quantities such as various moments. Geometrized unit system A geometrized unit system or geometric unit system is a system of natural units in which the base physical