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1500 questions
19
votes
2 answers

Why are truss bridges the way they are?

Just by taking a train ride across my home city I can see truss bridges like the one in above picture everywhere. There are numerous variations, but the most common design seems to be this. But why are they built specifically this way? I can…
S. Rotos
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19
votes
4 answers

Why does the microwave plate start in a random direction?

...or what type of motor is used there? I found this type of motor - usually powered with low-voltage AC (~12V), but at times with 230V, in several appliances that require very slow rotation and sometimes a fair momentum - a color-shifting lamp, the…
SF.
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19
votes
1 answer

Can we change steel properties by application of magnetic field while quenching?

Austenite is non magnetic while $\alpha$-ferrite and pearlite are magnetic. (Magnetic properties of pearlite vary as a function of carbon content) If a strong magnetic field is applied in a particular direction while the steel is being quenched…
Subodh
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19
votes
4 answers

How should I position two shelf supports for the best distribution of load?

I'd like to mount a shelf on the wall. I have two shelf supports to do so, like this: Relative to the shelf, where do I place the (blue) supports to achieve the best distribution of load?
Nico Schlömer
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18
votes
3 answers

Can wifi signal reception be improved by opening a door?

A wifi user is in a different room than the router. The computer is having a hard time connecting and receiving the wifi signal. Can the wifi signal from the router to the computer be improved by opening a door to the room where the computer is?
Mowzer
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18
votes
4 answers

Why are train brakes so complicated?

The concept is simple enough: no pressure in the train line has the brakes locked, full pressure is loose, and partial pressure drags accordingly. So if pressure is lost for any reason, the train stops. (or at least it's supposed to; more on that…
AaronD
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18
votes
10 answers

How did mechanical engineers work before SolidWorks?

I am studying a bunch of stuff related to mechanical engineering and am considering an eventual switch to the field after taking the necessary classes. I'm older, and I took drafting classes in high school and part of college. I'm familiar with the…
CL40
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18
votes
5 answers

Why are screw holes in most of the door hinges in zigzag orientation?

What advantage does it provide? Explaining with a figure would be helpful. I tried to draw a free body diagram and equated the sum of force and moments to zero, but still was not able to find out.
Qwerty
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18
votes
3 answers

Why do heavy trucks use air brakes?

I was having a discussion today, which led to the question why do heavy trucks still use air brakes? To my knowledge, it has been used for at least 40 years (I remember that as a kid), and apparently (I was told today but I haven't gotten around…
NMech
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18
votes
5 answers

Meshing of complex geometrical domains

When using the finite element method, I have always used either already meshed domains or very simple ones. From what I've heard, meshing complex geometries is often outsourced to specialized companies (as it is considered not to be an interesting…
Bérenger
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18
votes
2 answers

Why doesn't epoxy stick to silicone?

Why doesn't epoxy stick to silicone? Is there a type of epoxy that does?
Geremia
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18
votes
6 answers

Why do oil tankers heat crude oil?

About all those oil tankers off the coast of California … | Grist The giant ships burn fuel to keep lights on, power equipment, and heat the large volumes of crude oil resting in their tanks. I'm assuming that crude oil can't be heated in steel…
user24573
18
votes
1 answer

How to design a house to be cooled passively?

I live in Louisiana these days, in an area that is known for its numerous antebellum plantation homes (circa early 1800s). While touring one of these homes it was clear that almost everything about the house was designed around keeping cool in the…
18
votes
2 answers

What is the physical interpretation of the second term in the viscous stress tensor in the Navier-Stokes equations?

I have been searching for this answer for awhile. I've read numerous texts and even watched some lectures online, but often times this is never explained and just given. The viscous stress term in the Navier-Stokes equations looks…
18
votes
1 answer

Fracture patterns in tempered glass

While browsing a local news site, I stumbled upon this picture of a broken bus door. The glass was fractured due to a rock impact. As far as i know there are no heating elements on the window section in the picture. Now, what interests me is the…
shay s
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