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What is a Spiral Curve, and How is it Different from a Normal Curve?

I've heard the term spiral curve used to describe a section of highway that is more aesthetically pleasing to the driver's eye. However, I believe I've driven on enough road to say that I can't definitively tell the difference between any given…
gate_engineer
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How does pressure treatment affect the mechanical properties of lumber?

Pressure treated lumber is specified for many exterior applications because of its resistance to insect damage and fungal rot. But how does it compare to untreated wood, mechanically? For example, consider a rim joist supporting the ground floor of…
Air
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What makes the material travel through Archimedes' Screw?

...or in other words, why doesn't the material just stick to the screw, rotating in place, without progressing along its length? In the simplest case, the answer is obvious: gravity. If it's a granular or liquid material and the screw is tilted to a…
SF.
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I have inherited a product with inconsistent designs sharing the same part number. What do I do?

I am now in charge of a product line my company has been shipping for a decade. One of the previous product engineers was... shall we say, less than conscientious about sustainability and proper documentation. We have shipped hundreds of units, of…
Stephen Collings
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Derivation for bridge natural frequency estimate in Eurocodes

The Eurocodes gives the following equation for estimating a "simply supported bridge subject to bending only"*: $$n_0 = \frac{17.75}{\sqrt{\delta_0}}$$ Where $n_0$ is the natural frequency in hertz $\delta_0$ is the deflection at mid-span under…
thomasmichaelwallace
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How to correctly size the blades for a small educational wind turbine?

I want to design a small wind turbine that can be easily carried out of the classroom into the sports field in relatively low-wind conditions (5-15km/h) that can power a small ultra-bright 5V LED - just enough to show that it works. How do I…
jhabbott
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Does good electrical conductivity imply good thermal conductivity?

Typically materials which are good conductor of electricity are also good conductor of heat, and vice versa. Are there notable exceptions?
zxc
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Why does moving air feel cold?

I'm taking a thermodynamics class and had the following question. I was going to ask my professor directly, but it seems like a stupid question with a simple answer, so I thought I'd try my luck here in fear of embarrassment. When air flows through…
user01101001
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Replace mercury with silicone oil in diffusion pump

We have obtained an old mercury-vapor diffusion pump for high vacuum. However, we do not want to operate it with mercury in our lab due to health concerns (which is presumably the reason it was scrapped by the original owner). Instead, we plan to…
dominecf
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What is the difference between the Polar Moment of Inertia, $ I_P $ and the torsional constant, $ J_T $ of a cross section?

This question is so fundamentally basic that I am almost embarrassed to ask but it came up at work the other day and and nearly no one in the office could give me a good answer. I was calculating the shear stress in a member using the equation,…
William S. Godfrey- S.E.
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Schematic Diagrams for Mechanical Systems

Is there some sort of equivalent standardized schematical (topological) diagram -such as Piping and Instrumentation Diagram, Electrical Schematics, Process Flow Diagrams, etc.- for the realm of mechanical engineering? I just need to draw the overall…
joojaa
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How can large bridges be made resistant to earthquakes?

How can large bridges, with spans on the order of 1 km, be made resistant to earthquakes? I'm no expert on quakes, but there are at least two kinds of shaking: lateral and vertical. The vertical shaking in particular really worries me. I don't know…
DrZ214
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Foiling vortex traps around buildings

I have had three houses with right angles in the layout, and in each one that configuration causes vortices to form that suck in leaves, snow, and any debris blowing by and keep it in the nook of the building. Rough idea in the following sketch,…
feetwet
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Affixing a thermocouple to a surface

I'm looking for advice on how to attach a thermocouple to a metal surface in a fashion that's relatively temperature resistant (more-so than) glue. I've got some very fine gauge wire on hand to make the thermocouples and specialized spot welder…
Dan
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What causes the sound coming from electrical vehicles?

All the electrical vehicles I've ever ride make that humming sound (either cars or trains). What exactly causes that sound? Is it drag force in the gears? Is it a fan? Or is it because of the coils (see coil noise)?
cinico
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