text: The Bernoulli equation for incompressible 
  flow is most readily explained ,by accounting 
  for the energy of the~airflow within 
  the tube. 
  As the airstream has no energy added or sub- 
  tracted at any point, the sum of the potential 
  +id kinetic energy must be constant. The 
  kinetic energy of an object is found by: 
  
  If the density of the flow remains constant, 
  static pressure and velocity are the variable 
  quantities. As the flow approaches the con- 
  striction of station 2 the velocity must increase 
  to maintain 
  the 
  velocity increases the static pressure will de- 
  crease and the decrease in static pressure which 
  accompanies the increase in velocity can be 
  verified in two ways: 
  (I) Newton’s 
  
  “KE. =%MV= 
  
  where K;E. = kinetic energy, ft.-lbs. 
  M = mass, slugs 
  V’=velocity,  ft./set. 
  
  The kinetic energy of a cubic foot of air is: 
  
  K&x,, 
  
  laws of motion state the 
  requirement of an unbalanced force to pro- 
  duce an acceleration (velocity change). 
  If 
  the airstream experiences an increase in veloc- 
  ity approaching the constriction, there must 