A New Formula of Averaging Physical Quantities (Application to   calculation of the average radius of tapering tube and average flow velocity   in the tube)
  The traditional method of finding the average value of a physical quantity often gives wrong results. Another formula of averaging is derived which gives correct results. It is applied to calculation of the average radius of tapering tube and the average flow velocity in the tube. The new formula is applicable to many other processes. 
I. A. Stepanow