Working 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 is not, which makes it important.
Read more about Working Mass: Rockets and Rocket-like Reaction Engines
Famous quotes containing the words working and/or mass:
“It is not only a question of who is responsible for very young children. There is no longer anyone home to care for adolescents and the elderly. There is no one around to take in the car for repair or to let the plumber in. Working families are faced with daily dilemmas: Who will take care of a sick child? Who will go to the big soccer game? Who will attend the teacher conference?”
—Fran Sussner Rodgers (20th century)
“When over Catholics the ocean rolls,
They must wait several weeks before a mass
Takes off one peck of purgatorial coals,
Because, till people know what’s come to pass,
They won’t lay out their money on the dead—
It costs three francs for every mass that’s said.”
—George Gordon Noel Byron (1788–1824)