text: If the potential energy is represented by the 
  static pressure, p, the sum of the potential and 
  kinetic energy is the total pressure of the air- 
  stream. 
  
  H=p+% P V’ 
  
  where H=total  pressure, psf (sometimes re- 
  
  ferred to as “head ’ pressure) 
  
  p=static pressure, psf. 
  p=density, siugs per cu. ft. 
  V= velocity, ft./set. 
  
  This equation is the Bernoulli equation for 
  ‘incompressible flow. 
  to ap- 
  It 
  preciate that the term >$pV2 has the units of 
  pressure, psf. This term is one of the most 
  important in all aerodynamics and appears so 
  frequently t&it 
  is given the name “dynamic 
  pressure” and the shorthand notation “4”. 
  
  is important 
  
  q= dynamic pressure, psf 
  
  = jgpv2 
  
  With this definition it could be said that the 
  sum of static and dynamic pressure in the flow 
  tube remains constant. 