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
Mass flow rate These results are equivalent to the equation containing the dot product. Sometimes these equations are used to define the mass flow rate. Considering flow through porous media, a special quantity, superficial mass flow rate, can be introduced. It is related with superficial velocity, v, with the following relationship: The quantity can be used in particle Reynolds number or mass transfer coefficient calculation for fixed and fluidized bed systems. In the elementary form of the continuity equation for mass, in hydrodynamics: In elementary classical mechanics, mass flow rate is encountered when dealing with objects of variable mass, such as a rocket