Question

Surface roughness can be measured as either an arithmetic average (AA) or a root-mean-square (RMS) average. Which value is almost always greater for most surfaces?

Answer 1

Answer:

Root-mean-square (RMS)

Step-by-step explanation:

Arithmetic average is the average of all the values of the surface peaks and valleys.

$AA=\frac{\sum^n_{i=1}|y_i|}{n}$

Root mean square is the root of the sum of the squares of each of the values of the surface peaks and valleys divided by the number of values

$RMS=\sqrt{\frac{\sum^n_{i=1}{y_i}^2}{n}}$

where n = the number of values

So, the root-mean-square RMS is always greater than the arithmetic average (AA).