text: The force of thrust results from the accelera- 
  tion provided the mass of working fluid. The 
  is accounted for by the 
  magnitude of thrust 
  rate of change of momentum produced by the 
  powerplant. 
  rocket powerplant creates 
  thrust by creating a very large change in veloc- 
  ity of a relatively small mass of propellants. 
  A propeller produces thrust by creating a com- 
  paratively small change in velocity of a rela- 
  tively large mass of air. 
  
  A 