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1500 questions
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5 answers

When do I need to consult a professional engineer during a home renovation?

I am a homeowner who likes to save money by performing DIY work. When possible, I prefer to serve as my own general contractor to reduce the cost of a project. However, when I talk with professionals about my plans and ask for advice, they often…
Air
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Why does the manual to a 1989 TV dedicate almost a page to the "pin assignment" of the SCART connector?

It is a bit unclear whether this is the "user manual" or the "service manual", the latter may have only been used by service people, but nevertheless, why would it go through the specifics of the SCART connector, naming the purpose of each pin? Yes,…
M Clouden
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Why are multiple locomotives attached only to the front for larger trains?

For long freight trains and those that will be climbing to stations at higher altitudes, an extra or two locomotives are attached to the front. I've always wondered why. For argument's sake, if there are 30 bogeys each weighing 10 tons, the three…
Hussain Akbar
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How do the bubble oscillations in two-phase flows affect the dissipation rate of turbulent kinetic energy?

I am investigating the effects of bubble oscillations (calculated using the Rayleigh-Plesset equation for bubble dynamics) on the turbulence in two-phase flows. Since I am using cryogenic fluids, the thermal effects also play a role. I am trying to…
Karthik Venkatesh
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What are those large poles for that are always in front of US stand-alone store buildings?

Screenshot of a video where they are featured in the background: They appear to have no electronics built in, such as an electric charge station, or a parking ticket dispenser or something like that. They appear to just be large, solid metal poles…
Elijames Gosha
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Is there a reason (in terms of the physics involved) why it is better to push start a car in 2nd gear rather than 1st?

I am struggling to understand why it is recommended to push start a car in 2nd gear rather than 1st - in terms of the physics involved, I fail to see a reason why this would be the case. I have compiled where I am at currently with a for/against…
PhysicsGuy123
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Are pneumatic tires obsolete?

Adaptive suspensions with adjustment rates on the order of milliseconds are going mainstream in consumer vehicles. Air suspensions have been common on commercial trucks and some SUVs for some time. Why are pneumatic tires necessary or helpful on…
feetwet
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Why are lasers used for concentrated light applications instead of incoherent light sources?

Some laser applications consist simply of concentrating light into a small spot. Two example applications are laser welding and cutting. In these cases a CO2 laser is often used which needs a regulated power supply, a water cooling system, and a…
user3368561
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What limits a power plant's load gradient?

Each power plant has a load gradient characteristic, describing to what extent it can change the output of its generators in a given timeframe. Reading the literature, I know that, for example, a gas turbine power plant has a vastly higher load…
Technaton
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Looking for best material for a cryogenic ball mill cup and balls

I am working with a set of alloys that must first be ground up in a ball mill at cryogenic temperatures. It is important that no contamination makes it into the material and careful steps are taken to ensure this end. Unfortunately when we ran a…
eatscrayons
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Why does prestressing in trees make them stronger?

In "Structures: or Why Things Don't Fall Down" James Gordon talks about trees being prestressed with the outside in tension and the inside in compression. Why does it make a tree stronger to have it in tension on the surface and compression at the…
Voltron
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Is stainless steel plating possible?

Is there a method for plating steel with stainless steel? If so, is it chemical, electrical, or electrochemical? I did a quick search on the internet but was unable to find a service. I'm interested in applying a food safe finish to something that…
user379468
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Below what Froude number can I neglect wave-making resistance on a vessel?

I want to do some very simplified drag calculations on a vessel. My hope was that calculating the skin-friction resistance would be enough to get a good estimate of the surge resistance. Because wave-making resistance is very speed dependent, I…
Mika Sundland
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Why does column buckling occur when the load is parallel to the column?

I'm studying Euler's work on structural engineering from a book out of curiosity and it is mentioned that he developed a mathematical theory describing the buckling of columns under a parallel load (the weight-force of the load is directed down…
S. Rotos
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If the emergency brake in a train is broken, do the passenger car brakes still work?

Scenario: Suppose the emergency brake button in the cab of a train is not working. Would the emergency brake cords / buttons in the passenger cars still work? This question is inspired by this question on the SciFi StackExchange, asking why the…
Lars Ebert-Harlaar
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