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1500 questions
5
votes
1 answer
Determine elevation from the difference in air pressure
Given:
A problem in my thermodynamics text reads as follows...
The barometer of a mountain hiker reads $13.8$ $psia$ at the beginning of a hiking trip and $12.6$ $psia$ at the end. Neglecting the effect of altitude on local gravitational…
Jules Manson
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5
votes
1 answer
Why don't propeller designers use multiple profiles?
I'm designing a ducted fan, and I'm deciding on the airfoil profile. NACA 16-series profiles are well-suited to M > .5 or .6, but they're not particularly efficient at lower Mach numbers. On the other hand, older profiles, like Clark YM, work quite…
user1493362
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5
votes
1 answer
Volume change during tensile test
During tensile test, why does the specimen's(let's say mild steel) volume changes during elastic deformation and does not change during plastic deformation?
user34577
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5
votes
3 answers
Do scaled models reflect strength characteristics of full size
Lets say you want to build a bridge out of carbon fiber. This has never been never been done before, and it's super expensive stuff. So your goal is to use as little material as possible, but obviously your bridge still needs to have enough…
YAHsaves
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5
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4 answers
How should I go about adding holes to laser or water jet cut sheet metal?
I’ve been working on an electric Dirtsurfer project that has many parts to be made from folded sheet aluminium.
Obviously the sheet metal needs holes in it for bolts. The sheet aluminium will be either CNC laser cut or CNC water jet cut.
I’ve got…
Hannesh
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5
votes
2 answers
Do contiguous laser curtains exists? and if not are there any lenses that could spread a concentrated beam into a "planar" beam
The first photo is an example of a light curtain. I am certain that every individual beam is from an individual laser and receiver pair on both cases. Would it be possible to have one laser beam perhaps be directed from the top or side of the case…
AlanZ2223
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5
votes
2 answers
How is the long-term creep of a spring determined?
Spring Design
In spring design, there a a variety of parameters to consider. Some of the parameters are solely physical (wire diameter, coil diameter, length, etc.) and some are determined from the physical dimensions in combination with the…
hazzey
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5
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1 answer
Hovercraft design parameters
My washing machine broke down recently, and they replaced the motor. The old motor was not broken,
as far as I could tell; the sensor that told the CPU that the drum was balanced was what was out of
order. At any rate now I have a perfectly decent…
jamesson
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5
votes
7 answers
What makes scooters unstable at high speeds?
Scooters and skateboards are obviously meant for slower speeds, below 5 MPH. Typically if you go faster than that, it becomes harder and harder to control the scooter, and you will fall off. An example of this is the speed wobble, examples easily…
user16388
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5
votes
1 answer
What is a 'swept path' in a valve system?
I have been doing some research on valve systems for sample analyzers. In many of the valve systems' product documentation they refer to a flow path as 'fully swept'. From the context I can conclude that it increases the rate of purging a previous…
user16318
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5
votes
1 answer
How important is an ABET-accredited Engineering Degree in the EU (like Germany) or other countries that is not in North America?
I have an option to either attend Middle East Technical University - North Cyprus Campus (non-ABET accredited) or Mapua University (ABET accredited) in the Philippines to study Chemical Engineering as an undergraduate. I would personally prefer to…
CuriousHuman
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5
votes
1 answer
Bridge terminology - railing-like parapet
If a bridge has a parapet that is nota fully solid block and resembles railings with posts, as the following image
What is this type of parapet called?
What are the top, bottom, post, and hole of the railing-like structure called?
Thanks!
seamux
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5
votes
1 answer
How to draw a shear force diagram when two forces are acting at the same point
I am working on this question on my statics assignment:
Approximately at point B there are two forces, 20kN and 50kN.So far, I have only calculated global equilibrium and got the following…
AugieJavax98
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5
votes
1 answer
Will molten glass stick to a graphite shelf inside a kiln?
Normally, so called shelf papers are used or special coatings called kiln washes are used to prevent molten glass from adhering to the kiln shelf while it is being fired. This is expensive and time consuming. Can a different material be used that…
Walter Quigley
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5
votes
2 answers
Is the fill factor of a photo-voltaic cell constant?
An important factor in specifying the efficiency of photo-voltaic (PV) cells is called the fill factor (FF). It is defined as the ratio of the maximum power of the cell to the product of the open-circuit voltage $V_{oc}$ to the short-circuit current…
Moody
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