Errata for Environmental Systems Engineering

On page 174, Equation 10.2 is correct, but there is a serious error in Equation 10.2.

The book now says:

The first moment about an axis a is

a = ( x - a ) (x) dx ,           (10.1)

where is a moment with the subscript a denoting the axis. When a = 0,  ' is the mean. The second moment about the mean is

2  ( x - a )2 (x) dx .        (10.2)
This is wrong.

The correct equation is:

2  = ( x - ' )2 (x) dx .        (10.2)
 

On page 177, Equation 10.4 did not come out right. It should be: