In this article (and video above), we solve another civil engineering soil sample problem designed by Engineer in training, Enrique Ivers, LEED Green Associate, to help you prepare for your FE Exam. You can check out a previous soil problem we did here.
Question:
The specific gravity of a saturated soil sample is 2.75 with a total unit mass of 2500 kg/m³. The dry unit mass is most nearly:
Solution:
We should first assume that the total volume is 1 m³. Since we are interested in the dry unit mass, we should model the saturated soil as a two phase system of water and solid (reference p. 259 in FE Handbook v. 10.1)
Using the FE Handbook, we arrive at the following:
We can model the following:
Since this is the mass of solids in one m³ of soil, the dry unit mass is 2,357 kg/m³.
Answer:
The correct answer is D.
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I hope you found this week’s FE Environmental engineering exam prep question helpful. In upcoming articles, I will answer more FE Exam questions and run through more practice problems. We publish videos bi-weekly on our Pass the FE Exam YouTube Channel. Be sure to visit our page here and click the subscribe button as you’ll get expert tips and tricks – to ensure your best success – that you can’t get anywhere else. Believe me, you won’t want to miss a single video.
Lastly, I encourage you to ask questions in the comments of the videos or here on this page and I’ll read and respond to them in future videos. So, if there’s a specific topic you want me to cover or answer, we have you covered.
I’ll see you next week.
Anthony Fasano, P.E.
Engineering Management Institute
Author of Engineer Your Own Success
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