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1500 questions
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7 answers

Why are bulldozers so slow?

Tracked-type tractors and bulldozers are very slow engineering vehicles. Their top speed is less than 15 km/h and when pushing it is even lower (< 5 km/h). For example: the Caterpillar D9's top speed in forward gear is 11.0 km/h while in reverse…
Triceratops
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How does one go about building an underground structure without concrete?

I was reading an article that was linked on another site I frequent on "India's forgotten stepwells", which are basically elaborate wells with stairs to go down to the water level, sometimes 10 m or so below surface (maybe more, looking at the…
Roel
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Can a very bright light attract an incoming laser guided weapon?

I would like to know if a very bright light will attract an incoming laser guided weapon such as a laser guided missile. Say for example that a tank has a six-foot pole on the top of it and attached to the end of this pole is a high-voltage carbon…
user33377
10
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3 answers

Could air-launched space planes reach escape velocities?

Rockets like the Ariane 5 weigh hundreds of tons, but with about 85% of that weight being fuel, the payload fraction is only about 3% (~10-20 tons). Virgin Galactic is building suborbital space planes, mostly for tourism purposes. They fly at about…
NoDataDumpNoContribution
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What happens from B to C in this stress strain diagram of mild steel?

Image Source: https://mechtics.com/design/strength-of-material/stress-strain-curve-for-mild-steel-with-defination-of-stress-and-strain/ I know that A is the proportional limit, B is the elastic limit. Up to B if the loading is removed the material…
Harshit Rajput
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What kind of metal are eye glasses frames made from?

I've noticed that prescription eye glasses frames are often made from metal that is quite rigid. It's surprisingly difficult to bend the metal, despite how thin it is. And if it does bend, it doesn't seem to weaken much when bent back and forth. Is…
User1974
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Why don't motorcycles have as good a turning radius as bicycles?

The question is about why are motorcycles not manufactured with handlebars that can turn to great degrees like a bicycle. In most motorcycles, you hardly have a steering angle of about 20-30 degrees, whereas on a bicycle, you can even go beyond 90…
Siddh Aarth
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How do vending machines prevent people from stealing goods?

I never understood mechanically how a vending machine prevents people from accessing goods through the dispensing panel. From what I understand it's not a locked door that unlocks only upon payment, dispenses goods and then re-locks. In my…
Sidharth Ghoshal
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Preventing condensate backup at startup with orifice (venturi) steam traps on medium pressure batch process mains?

I am working with 1" medium pressure steam mains (45 psig) for a batch process. Time between batches is usually short (to the order of minutes) but depending on the day the delay can be hours, and even longer over weekends or holidays. We recently…
jmac
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Detailing Fixed Cotton Duck Bridge Bearings

I'm looking for a justification for the use of cotton duck bearing pads without a sole plate. I'm specifically considering their use with precast I-girders. Say I have a two span bridge, simply supported for dead load, with expansion bearings at the…
CableStay
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What is the focal distance of an optical mouse?

I am trying to build an optical sensor for my old school, state property, standard french watt-o-meter. EDF ( Electricité de France ) has a gig which turns a wheel depending on watt consumption. The higher the wattage, the faster a tiny disk turns.…
Martin
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Hydraulic siphon spillway entry and exit velocity magnitude and profiles

I am working on the hydraulic seawater flow though a siphon spillway. My task is to determine at a location in front of the spillway the flow velocity and profile when The flow enters the spillway The flow exits the spillway See attached a…
Ruudc
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Why are some public benches made with arm rests that waste so much space?

While watching a YouTube video today, I noticed this public/park bench somewhere in the USA: It looks strange to me the way the arm rests on each side are so far into the bench, wasting a rather large combined space if you count both sides. Why…
B Burnie
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Saving RAM Memory when writing to 2K page size NAND flash

I am writing a driver for the Samsung K9WAG08U1D NAND flash chip. The specification of the memory chip mentions it has a page size of 2048 bytes (2kB). I am using a TI MSP430F2619 which has 4096 Bytes (4kB) of RAM. This means I need to allocate a 2k…
prasad
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Forgotten time units

As my kids are counting down to Christmas, I came to wonder how did people measure time through history. More precisely I wonder about unit systems for precision time keeping of years past gone. I am wondering this, because the other two most…
NMech
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