# Engineering Centroid Problem

• Aug 26th 2009, 07:48 PM
Cesspit
Engineering Centroid Problem
$\displaystyle Centroid = \frac {\int_0^h y\frac {b}{h}(h-y)dy}{\int_0^h \frac {b}{h}(h-y)dy}$

I have the answer which is $\displaystyle \frac {\frac {1}{6}bh^2}{\frac {1}{2}bh}$ which produces $\displaystyle \frac {h}{3}$ as you may know that is a triangle.

However I cant get the same answer, infact I appear to be way off. Can anyone suggest how to integrate this problem? maybe even just the top would be great help.

Thanks to those who can help.
• Aug 26th 2009, 07:53 PM
nirax
what is the probelm ?? both the num and denom are polynomials ... u just have to use the formula mindlessly .. where r u stuck ?
• Aug 26th 2009, 08:00 PM
Cesspit
on the graph attached the triangles line is $\displaystyle y = \frac {h}{b} (b - x)$ using the standard equation for calculating the y value for the centroid.
• Aug 26th 2009, 08:02 PM
Cesspit
I am having trouble integrating the formula in terms of y to get the answers. I cant get the same answer I am getting very different values
• Aug 26th 2009, 09:06 PM
nirax
what r u getting ???
• Aug 26th 2009, 09:29 PM
Cesspit
The centroid of the triangle, or you might know it as the first moment of area.