Advantages of hollow vs solid cross-sections in beam bending

[headshrinker]

Homework Statement

Explain the advantages of using hollow cross sections against solid sections in beam bending applications.

Homework Equations

None

The Attempt at a Solution

I know this has something to do with the Neutral axis and the second moment of area for the beam but i don't know how!

please help!

 

[chrisk]

Quantitatively, evaluate the moment of inertia of a hoop about an axis in the plane of the hoop passing through the center of the hoop (neutral axis contains the centroid if no net tension or compression of the beam exists) with a mass M. Then evaluate the same moment for a solid circle of equal mass. This geomtery is easy to evaluate. Qualitatively, you can compare the radius of gyration of the two cross sections about the neutral axis. What do you conclude about their moments? How is bending related to moment or radius of gyration?