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How to calculate flow rate of water through a pipe?
If a water pipe is 15 mm diameter and the water pressure is 3 bar, assuming the pipe is open ended, is it possible to calculate the flow rate or water velocity in the pipe?
Most of the calculations I have found appear to need 2 of these: diameter,…
Richard
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Why do we even use engineering stress?
Surprisingly this hasn't been asked before, so I must be missing something simple.
We use engineering stress and engineering strain in this eq. Stress = (Young's modulus) × (strain). This eq. is used in analysis of bending beams, twisting shafts…
Jessica
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How to determine the characteristic length in reynolds number calculations in general?
I understand that the reynolds number is given by the expression $Re=\frac{\rho v L}{\mu}$, where $\rho$ is the density, $v$ is the fluid velocity and $\mu$ is the dynamic viscosity. For any given fluid dynamics problem, $\rho$, $v$, and $\mu$ are…
Paul
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What kind of math do engineers really use?
I am from the mathematics StackExchange section, many of my students are engineering students at University. I was wondering what kind of calculus do you real engineers use? I have known two engineers. One from airplane design and another from…
Nicolas Bourbaki
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Why are hyperboloid towers not popular anymore?
Hyperboloid towers were very popular in the end of 19th and the first half of 20th centuries - water towers, powerline anchor towers, sometimes tall radio towers were built using this design. The claimed advantage is using less steel compared to…
sharptooth
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What is this small rotating part from a cell phone?
What is this tiny rotating piece of hardware that I found inside my Samsung GE1202? It has E9C written in blue on it.
PyRoss
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2 answers
What is this large steel structure used in excavation?
I keep seeing these large rectangular structures on job sites they put in the ground.
I'm guessing something for strengthening the surface structures?
v15
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How do I size metal plates to get the correct dimensions after folding?
I am designing a metal plate that will be laser-cut (or machine-cut) and then folded. I want to know how to size the pre-folded plate in order to get the right dimensions after folding.
My actual part is not exactly like this (I simplified it for…
jhabbott
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Quantifying inertia on the electricity grid
A lot of discussion about the modernisation of electricity systems is about "inertia". This is usually a qualitative discussion about how turbines (in hydro, coal & gas plants) with lots of kinetic energy in the form of angular momentum and fast…
410 gone
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Purpose of spheres and fins on submarine propeller
On a recently launched Russian diesel-electric submarine, the rear propeller has two distinct features. You can see spheres at the base of every propeller blade:
Also, the trailing edge of the shaft has four adjoining fins in line with the axis of…
Rupert Reckless
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How should the public raise questions about unsafe structures in the United States?
In a program on NPR that I was listening to, there was a bit about a bridge that from the description sounded to a layman as unsound and is still in use. The program described it as an old wooden railway (and I'm aware that has its own set of…
user348
14
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Why is Mach 0.3 the threshold separating compressible and incompressible flow?
I've read that Mach 0.3 is pretty much the upper limit for treating air as an incompressible fluid. The sources I've read seem to treat this as a given, without proof or justification.
Why is this the limit? Is there a mathematical justification…
Paul
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What are some cost-effective metal substances that can wet glass?
A highly desirable property of metals like gallium and indium is that they are able to wet glass.
Normally, as metals, they wouldn't be able to form an airtight seal when in contact with glass. But they are able to do so, and they can be used in…
APerson
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When do I need to consult a professional engineer during a home renovation?
I am a homeowner who likes to save money by performing DIY work. When possible, I prefer to serve as my own general contractor to reduce the cost of a project. However, when I talk with professionals about my plans and ask for advice, they often…
Air
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Why does the manual to a 1989 TV dedicate almost a page to the "pin assignment" of the SCART connector?
It is a bit unclear whether this is the "user manual" or the "service manual", the latter may have only been used by service people, but nevertheless, why would it go through the specifics of the SCART connector, naming the purpose of each pin?
Yes,…
M Clouden
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