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
Velocity gradient analysis, the dimensions of velocity gradient can be determined. The dimensions of velocity are formula_4 , and the dimensions of distance are formula_5. Since the velocity gradient can be expressed as formula_6. Therefore, the velocity gradient has the same dimensions as this ratio, i.e. formula_7. In 3 dimensions, the gradient, formula_8 , of the velocity formula_9 is a second-order tensor which can be expressed as the matrix L: formula_11 can be decomposed into the sum of a symmetric matrix formula_12 and a skew-symmetric matrix formula_13 as follows formula_12 is called the strain rate tensor and describes the rate of stretching