# Recent content by Facial

1. ### Earth's Internal Heat Source

This is a response to a question in Scientific American given by Dr. Quentin Williams who specializes in the deep interior. I searched "Why is the earth's core so hot" on Duckduckgo. (I'm not sure if current posting guidelines allows me to give links to periodicals?)
2. ### Automotive Random Vibration and PSD spectrum profiles

There is a great article by Tom Irvine on why the units are unusual. I have myself wondered this for some time, working in this field. The units are generally motivated by the practical considerations of signal processing, viz., getting a meaningful measure of amplitude that is free from the...
3. ### News Stephen Hawking has Died - March 14th, 2018

RIP Dr. Hawking! I have seen him as a source of inspiration for years. I think he is still scientifically underrated.
4. ### Earth's Internal Heat Source

I've been wondering about this question for some time now. There are the following two contributors: ~~~~~~~~~~~~~~ 1. Heat left over from the planet's initial formation. In the early 19th century Lord Kelvin estimated the temperature based on a homogenous sphere of uniform initial temperature...
5. ### How much lb could an average person push?

This is really a question of two related parameters: 1. How heavy is the average person? 2. What is the average coefficient of static friction (for all combination of surfaces), i.e., what is 'typical'? When you answer these two, you should be able to extract an answer.
6. ### Subjects needed in High School for Aerospace Engineering

Remember how to do calculus, matrices, and all that. Math is an indispensable tool, but HowlerMonkey also underscores an equally important point: we need to be able to communicate effectively, succinctly, and with proper grammar and spelling.
7. ### Stress Calculation on trailer legs

There are quite a few other corrosion-resistant materials out there, some of them non-ferrous. Even within the family of austenitic steels you can consider 304L or 316L in the 1/2-hard 3/4-hard or full hard or extruded Cond. F grades as alternatives. I can also see where Chris is going... those...
8. ### Coefficient of friction in soap?

What are the static and dynamic friction values for dry and wet soap? I can't find these things anywhere on the net, except for an assumption of the kinetic value of 0.06. If someone has access to an extensive data sheet on frictional values, then that would help greatly. Thanx
9. ### Use of steel powder in composites

How effective is using steel powder in a polymer/ceramic composite matrix? I am wondering this from observing this product called Faststeel which is one of those epoxy putty sticks that claims to be steel-reinforced. I actually think that it will make a material stronger than the matrix...
10. ### Material with best tensile strength to weight ratio?

Kevlar and basalt fiber are two contenders on the practical scale; carbon nanotubes are the strongest on the laboratory/R&D world. But while there are many fibers that exist with high tensile strength, I still think man has not found any composite, polymer, ceramic, or metal that can come...
11. ### Space Density

If I remember correctly, the average density of space is something on the order of one atom per cubic centimeter.
12. ### Can a nuke power plant just blow up?

You can have a steam explosion. But a nuclear one? No. The uranium used in reactors is not enriched enough.
13. ### Rust Production

Or better yet : find an old alley. There are dumpsters with lots of rust chips that can be taken from the ground.
14. ### Material Choice: Durability, Cost, Weight

I would aluminum alloy is your best bet if you're making a robot. Normally its pneumatic operations and small motors that power it would want less burden on the weight. But it depends. If you want strength per volume, steel. Simply put, if you have to handle cyclic loads on small parts...
15. ### Heat-resistant materials

Yes. This is exactly what I want to find out. Is there something wrong with the mechanical behavior of MgO at high temperatures?