# What does $\bar{x}_{\textrm{el}}$ represent?

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1. Apr 6, 2015

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In the context of centroids and moments, what do $\bar{x}_{\textrm{el}}$ and $\bar{y}_{\textrm{el}}$ represent?

For example:

$$\bar{x}L = \int \bar{x}_{\textrm{el}}dL$$

2. Apr 7, 2015

### mathman

The integral itself looks like a first moment, where the integrand is a function of position. I have no idea where this came from, so I can't go into any more detail.

3. Apr 7, 2015

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Here are some resources that utilize this notation:

1. (page 1) http://www.sut.ac.th/engineering/Civil/CourseOnline/430201/pdf/05_review.pdf
2. Vector Mechanics for Engineers:Statics and Dynamics by Ferdinand P. Beer & E. Russell Johnston J.
Below is an example problem Beer's

4. Apr 7, 2015

### SteamKing

Staff Emeritus
xEL and yEL represent the location of the centroid of a tiny element of length dL or a tiny element of area dA used to calculate the first moments of length or area.

Study pp. 1 and 2 of the link carefully.