moertle

I wrote this post before I saw the other one. I have actually figured it out. Thank you for taking your time to respond.

Studiot, I have a question regarding this post. I am currently working on the problem and cannot figure out the equation to use for this problem. You mention the simple beam theory but I cannot seem to find the correct equation from that theory to use for this question. Can you please elaborate? Moertle

A granite plate freely supported at its ends spans a gorge 20m wide. How this does the plate have to be if granite fails in tension at 20 MPa? Assume density is 2700 kg m^3. This is a question in the textbook "Geodynamics" by Turcotte and Schubert. It is a question in chapter 3 (Elasticity and Flexure) question 3-14. I've been working on this for two days and cannot figure out how to solve the question. I know the answer is 0.405m from the back of the book. I cannot figure out the equation to use for the problem. I have tried multiple equations from the book and I haven't figured out which equation to use. Thanks!