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1500 questions
26
votes
11 answers
From an engineering point of view what are the downsides of a too accurate model?
I was wondering, from an engineering point of view, for what reasons can too much accuracy in modeling be detrimental?
From a scientific point of view it seems like it's almost always a benefit, apart from when you need to take less computation…
TheGuest
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25
votes
12 answers
How to stop water flow in a siphon?
I have assembled a small DIY drip-irrigation system for my terrace garden. Please have a look at the attached image. I switch on a small pump to start the drip-irrigation system and then switch it off. But even after that, the water keeps flowing…
javed
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25
votes
2 answers
Why would you launch a large ship by dropping it sideways?
I'm referring to the process shown in this video:
https://youtu.be/Quyr5R1Rbfw?t=20
Or this image from Wikipedia:
In it, a large warship is launched into the water by essentially dropping it sideways down some ramps and off of a pier. The ship…
aroth
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25
votes
3 answers
Why does this fence have a kink?
The image below shows a style of fence that I've seen frequently around train tracks. If you look closely, you will see that between the third and fifth horizontal wire from the top, the vertical wires have a kink in them where they run diagonally…
Yly
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25
votes
8 answers
Why are rear wheels not placed at the extreme rear of a bus?
In some cars, I have noticed the rear wheels are located at the extreme rear of the vehicle. However, I have noticed that the rear wheels of buses are always located about 1/4th of the way forward from the rear. What is the reason for this?
Biju
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25
votes
5 answers
Why don't hydroelectric plants use cascades of turbines instead of single turbines?
In a gas turbine engine there're multiple sets of blades - one set after another and combustion products pass all the sets and each set of blades gets some of the power. This increases utilization of power from burning gas.
Meanwhile hydroelectric…
sharptooth
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25
votes
2 answers
Why doesn't a lightning strike destroy the lightning rod?
Lightning strikes have been known to cause massive amounts of damage. The stats on a lightning bolt are:
current levels sometimes in excess of 400 kA, temperatures to 50,000 degrees F., and speeds approaching one third the speed of light
These are…
hazzey
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24
votes
5 answers
How do ball bearings not crack from a load concentrated on an infinitesimally small point?
How do ball bearings last? Most bearings in a standard hub (bottom of the image) are not actually taking a load. Only the single ball that happens to be at a particular location while spinning takes 100% of the load. If the bearings were cylindrical…
Sam7919
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24
votes
5 answers
Why exactly does a washer help distribute the stress around a bolt?
Usually the reason for having a washer under a bolt head is stated to be that it helps to evenly distribute the stress to the clamped material surface. But why is this?
I would understand if the washer was significantly larger than the bolt head.…
S. Rotos
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24
votes
2 answers
What is the purpose of these "steps" in rivers?
I have seen a number of structures within rivers, which resemble steps, and which allow the water to cascade down them instead of flowing naturally down the course of the river.
Example 1: River Avon in Bath
Example 2: River Seine in Paris (from…
March Ho
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23
votes
10 answers
Why not put servers in a refrigerator?
Recently I was thinking about home improvement, and one idea that is haunting me is that I could use some kind of refrigerator for gaming consoles and laptops.
The obvious benefit is that it maintains a constant low temperature. Also, the doors…
Aleksandr Medvedev
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22
votes
4 answers
What is a reason that handlebars fit to a motorcycle and steering wheel fit to a car?
What is the reason that handlebars are installed on motorcycles and steering wheels are installed on cars?
Notice that the way to use both handlebars and steering wheels are quite similar, but a steering wheel allows for much more rotation than a…
fronthem
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22
votes
7 answers
Why do wooden gate designs recommend a brace under compression instead of tension?
Looking at guides for building wooden frame gates I almost always find the following design recommendation:
The idea is that the cross brace will distribute load from the top outside corner into the bottom of the hinge bracket. I understand this…
jesse_b
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22
votes
4 answers
How does turning off electric appliances save energy
We all know if we use less electricity we save energy.
But the energy we're getting is result of burning (not necessarily the literal meaning) the fuel. Even if we don't use that energy that fuel is gone forever. (Except saving money on bills)
My…
ShivCK
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22
votes
4 answers
Would it make sense to have a 12V lighting circuit in a house?
Modern LED bulbs must convert the standard household supply (for example $240\text{V AC}$ in the UK) into a DC supply at a lower voltage (usually $12\text{V DC}$ I think) for the LED array. This is done on a per-bulb basis.
Does this waste much…
jhabbott
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