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1500 questions
93
votes
4 answers

Why do color TVs make black and white snow?

If you let a color TV display something from an unplugged display port, it displays snow, right? Randomly varying black or white pixels on the whole screen. My guess was that the television was decoding the noise from the unplugged wires as a video…
Axel B
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10 answers

Why do glass windows still exist? (Why haven't they been replaced by plastics?)

Glass is fragile and impractical to transport, install and repair. Even worse, glass kills and hurts people when it breaks. Falling to the streets like guillotines during earthquakes and bomb raids. During wars people put tape on their windows to…
LocalFluff
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Why is kVA not the same as kW?

I thought my electric car charging unit uses 6.6 kW of power. However, I found the label and it actually says 6.6 kVA. When I saw this I thought something along the lines of... Well, $ P=VI $, therefore kVA must be the same thing as kW... strange,…
jhabbott
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55
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9 answers

Why do cars have mirrors for rear view rather than cameras?

Despite having so much technological advancement, I wonder why cars still uses mirrors (right and left side of the driver) for the rear view. These mirrors can be easily replaced by cameras and monitors (display for the driver). I noticed such…
parag
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54
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13 answers

Are toasters really electrified inside of the "slots"?

My mother was born 1950. Me in the mid-1980s. All my life, she's been saying that I must never stick a metal object, such as a knife, into the toaster, because it will electrocute me. I've always been scared of this, even though it seems highly…
Anupam Strane
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52
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2 answers

How was Volkswagen able to trick the lab pollution test?

The recent Volkswagen pollution test cheating scandal has shocked many people with its widespread extent as well as how it was hidden for so many years. Last year, the International Council on Clean Transportation (ICCT) in Washington DC…
March Ho
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9 answers

My customer wants to use my products to do something unsafe. What is my ethical obligation?

We sell products that attach to a motor drive's DC bus. We also formerly sold diode kits that let you hook one product up to multiple drives. We stopped selling those diode kits because they were unreliable with modern hardware, and we had better…
Stephen Collings
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9 answers

Is it possible for a bicycle chainwheel to have a fractional number of teeth?

Background In the world of bicycle motocross, also known as BMX racing, gearing is a hotly-debated topic. Since the bikes are all single-speed, gear ratio is a fixed number defined as chainwheel / cog (front gear divided by rear gear). Altering your…
eckza
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4 answers

Transmitting power over long distances what is better AC or DC?

I found this answer to a related question. The part of the answer that's confusing me is: Transmitting DC power over a long distance is inefficient. Thus AC supply is a far more efficient to transmit power. According to Siemens it's quite the…
Arraval
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40
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10 answers

Is it possible to build a perfectly spherical Prince Rupert's drop?

Prince Rupert's Drops are glass objects created by dripping molten glass into cold water. While the outside of the drop quickly cools, the inside remains hot for a longer time. When it eventually cools, it shrinks, setting up very large compressive…
Vladimir Cravero
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39
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2 answers

What is the purpose of these diversions in a natural gas line?

The campus where I work has a long covered walkway (~.5 mile) which has several labeled pipes running under the roof (chilled water, fuel oil, air...). All of the pipes run dead straight except for the natural gas lines, which have little loops…
Gretchen
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39
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6 answers

What is the purpose of these “partially filled in” locomotive wheels?

I recently visited a railway museum with a lot of Soviet-era locomotives. The picture below shows the wheels on a locomotive from the 1930s or 1940s. Some of the wheels are thicker on one side (as it it were a partially filled cup). What is the…
adam.baker
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36
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12 answers

What are the pros and cons of a traffic circle versus a traffic light intersection?

The debate of traffic circles (also called roundabouts or rotaries) versus traffic light intersections has been in progress for a while. Those in favor of traffic circles say that, among other things, that they are safer than traffic light…
APerson
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35
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3 answers

How fast does solid waste fall in vertical drain pipes?

Some building are really tall, if you flush the toilet and the contents go into a pipe and straight down, there could be a lot of energy, potentially enough to cause harm to the sewer pipe at the end of the fall. I know that in my home, the pipe…
James Jenkins
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35
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3 answers

Why are railroad tank cars bent in the middle?

I recently noticed that the cylindrical shape of a railroad tank car is not completely straight but has a bend in the middle. The entire tank is a bit lower there. What's the reason for this bend? This is also visible on the drawing of a DOT 117…
Lukas_Skywalker
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