Torque Torque Torque, moment, or moment of force is the rotational equivalent of linear force. The concept originated with the studies of Archimedes on the usage of levers. Just as a linear force is a push or a pull, a torque can be thought of as a twist to an object. The symbol for torque is typically formula_1, the lowercase Greek letter "tau". When being referred to as moment of force, it is commonly denoted by "M". In three dimensions, the torque is a pseudovector; for point particles, it is given by the cross product of the position vector (distance vector)
Commonly used gamma-emitting isotopes into a tumor such as a breast tumor, and the tumor is irradiated by gamma ray photons from the wire. At the end of the treatment the wire is removed. A rare but notable gamma source is sodium-24, this has a very short half-life but it emits photons with very high energies (>2 MeV). It could be used for radiography of thick steel objects if the radiography occurred close to the point of production. In common with Co-60 and Ir-192 it is formed by the neutron activation of the commonly found stable isotope. Americium-241 has been used as a source