© Dr. Steve Rapp, 2005

Conserved Quantities

nMany engineering quantities (such as mass, charge, momentum, energy) are conserved.
nFor these quantities, the
universal accounting equation
reduces to:
nFinal Amount – Initial Amount = (Input – Output) or Accumulation = Net Input.
nFor a system at steady
state and with conserved quantities,
the equation reduces to 0 = Net Input.