Working mass Working mass Working mass, also referred to as reaction mass, is a mass against which a system operates in order to produce acceleration. In the case of a rocket, for example, the reaction mass is the fuel shot backwards to provide propulsion. All acceleration requires an exchange of momentum, which can be thought of as the "unit of movement". Momentum is related to mass and velocity, as given by the formula "P = mv," where "P" is the momentum, "m" the mass, and "v" the velocity. The velocity of a body is easily changeable, but in most cases the mass
Event (particle physics) beam and their average velocity), and the rate and luminosity of the experiment. Individual particle physics events are modeled by scattering theory based on an underlying quantum field theory of the particles and their interactions. The S-matrix is used to characterize the probability of various event outgoing particle states given the incoming particle states. For suitable quantum field theories, the S-matrix may be calculated by a perturbative expansion in terms of Feynman diagrams. Events occur naturally in astrophysics and geophysics, such as subatomic particle showers produced from cosmic ray scattering events. Event (particle physics) In particle physics, an event refers