Why is this specific air intake design so common in modern stealth jets? |
- Why is this specific air intake design so common in modern stealth jets?
- Why do scientists use rudimentary outlines of images when using the preferential looking paradigm as opposed to actual photos?
- I just read that Venus has about 90 atmospheres pressure at the surface. Knowing that Venus is about the same size as Earth, how can it have such a deep, or heavy, atmosphere?
- How can a drum spinning with tubes entering and exiting the same point not twist the tubes around each other?
- Can you "swim" in space? In a space station?
- Why is the logarithm formulation in Self Information optimal compared to other functions? (Information Theory)
- Why do electrons and protons have precisely equal but opposite electrical charge but with different masses?
- What is the theory behind large velocity/frequency widths for masers?
- What qualities make an animal more likely to be domesticated?
- How do Earth's Satellites stay in orbit? [Physics]
- Is it common to use PSI even in Metric countries?
- Do animals that have ranges or territories continually try to expand their range?
- How do we know what sea surface temperatures were in the late 1800's and even the early 1900's?
- If you are looking at an LED which changes color at a given interval, how short would that interval have to be to have the colors appear as only white light?
- How do the joints of a hummingbird deal with all the wear?
- How long do solar panels last before needing to be replaced and is this currently a barrier to investing in solar in terms of cost efficiency?
- How are quarks arranged inside protons/neutrons? Are there quark orbitals/clouds, just like how electrons are arranged atoms?
- What causes some rocks/minerals to naturally form with right angles and straight edges?
- Over what distance does rayleigh scattering have an effect distinguishable by naked eye?
- Why does wood turn "grey" after being outside long enough?
- How far can a human scream/ howl travel?
- Why do some 'old' people look very young for their age?
- What happens to a metal lattice as an EM wave hits it?
| Why is this specific air intake design so common in modern stealth jets? Posted: 08 Feb 2017 07:37 AM PST https://media.defense.gov/2011/Mar/10/2000278445/-1/-1/0/110302-F-MQ656-941.JPG The F22 and F35 as well as the planned J20 and PAK FA all use this very similar design. Does it have to do with stealth or just aerodynamics in general? [link] [comments]  |
| Posted: 08 Feb 2017 10:59 PM PST In an experiment called Do Infants Possess an Evolved Spider-Detection Mechanism? scientists show rudimentary outlines of spiders to infants and track the infants's eyes to test if humans have an innate spider-detecting mechanism. They show reconfigurations of the schematic spider image as well to see if the infants have a tendency to pay more attention to the original spider schematic than to the reconfigured "random images. I was wondering why they had to go through the whole process of creating and using a schematic spider as opposed to just using pictures of actual spiders. At first I thought they only did this so that they could reconfigure the image, but then I realized they could easily do that with a picture of a real a spider. Later they used pictures of real spiders to prove that infants recognized the schematic spider as a spider, as opposed to seeing them as unrelated shapes. Thanks in advance for answering. [link] [comments]  |
| Posted: 08 Feb 2017 09:03 PM PST |
| Posted: 08 Feb 2017 08:05 PM PST I am a nursing student, and today I was shown an aphairesis machine. The thing that blew my mind was the centrifuge. It had the whole blood coming in, and the plasma and red blood cells coming out 2 tubes, so 1 tube entering, 2 tubes leaving. They are continuous with no breaks. The RN showing it to me couldn't explain it to me and I can't figure it out. Here is a picture of the thing not in motion: http://imgur.com/o36RgZZ Here is a gif of it in motion: http://imgur.com/omHPJoR EDIT: Here is a video of a full unit showing plasma donation. it doesnt show the full disassembly of the unit unfortunately. Its to give you an idea of whats up top. https://www.youtube.com/watch?v=s4MSK4Q-El4 [link] [comments]  |
| Can you "swim" in space? In a space station? Posted: 08 Feb 2017 07:34 PM PST So I was watching Chris hadfield singing in the space station, "standing" still keeping contact with the station with his feet. For a moment he let go and stood still, floating. This is where I wondered, what if he is out of reach of anything in the station? if he can't pull nor push himself. He is breathing freely (so there are gaz) so I guess he could "swim" inside the space station. It wouldn't be very useful because of the low density but I suppose he could try. Does that mean that in space, if you're not moving relatively to something that could save your life 2 meters away, you couldn't do shit about it? (looking for answers on reddit, I found people suggesting farting as a way to generate thrust). Thank you for your replies. [link] [comments]  |
| Posted: 08 Feb 2017 09:54 PM PST Recently I read up a bit of Information Theory which talks about the concept of Entropy. However I am unable to find a satisfying answer that the logarithm of the event probability, i.e. log(1/p), is the optimal choice. Now I know that it has several attractive properties including:
From the data compression/transmission standpoint, it makes sense to allocate less number of bit for frequent outcome but more for rare event. If that is the rationale behind self information, then what stops us from allocating even more to rare event, say move another 1 bit from the frequent event to rare event? I suppose it is related to some kind of lower bound on how many bit I have to allocate for any event. [link] [comments]  |
| Posted: 09 Feb 2017 12:58 AM PST |
| What is the theory behind large velocity/frequency widths for masers? Posted: 08 Feb 2017 09:01 PM PST I was going through this paper where the velocity of the maser is on the order of 80 000 km/s due to cosmic expansion (z = 0.265). But as you may see in Figure 1, the velocity width of the signal is about 2200 km s-1 . When plugging those values for this OH transition into here, I get frequency widths on the order 10 MHz. Are not these frequency widths quite large for megamasers? I was under the impression these masers resulted in narrow lines. Also, I was led to believe there is velocity coherence in masers, but in this case, how can a maser have a velocity width of 2200 km s-1 ? Would not the molecules moving at different velocities result in collisions and dephasing throughout the masing region resulting in thermal equilibrium eventually? Even when looking at Figure 1, why does there appear to be two peaks as opposed to a single pulse as normally observed? And finally, can the velocity widths theoretically be even higher than 2200 km s-1 ? I suppose a better initial question is what is causing these widths of 2200 km s-1 in the first place? [link] [comments]  |
| What qualities make an animal more likely to be domesticated? Posted: 08 Feb 2017 02:54 PM PST Why can't all animals be domesticated? Are there any animals that could be domesticated but are not yet? [link] [comments]  |
| How do Earth's Satellites stay in orbit? [Physics] Posted: 08 Feb 2017 06:09 PM PST I understand that there is a sling-shot effect, but what I don't comprehend is how objects that stay within the orbit of Earth don't either get pulled towards the planet from going too slow, or get shot into,space from going too fast. in other words, how to these satellites maintain the correct speed? [link] [comments]  |
| Is it common to use PSI even in Metric countries? Posted: 09 Feb 2017 03:07 AM PST PSI seems to be used in general conversation, even outside the USA. Thanks! [link] [comments]  |
| Do animals that have ranges or territories continually try to expand their range? Posted: 08 Feb 2017 04:20 PM PST For example, lions have their pride areas. Does the actually area the pride controls increase over time (barring competition) or only stay large enough to support the pack and adequately protect? [link] [comments]  |
| How do we know what sea surface temperatures were in the late 1800's and even the early 1900's? Posted: 08 Feb 2017 10:52 AM PST I guess more specifically:
[link] [comments]  |
| Posted: 08 Feb 2017 10:54 AM PST Asking for a project, just need a general limit to color perception in time. Thanks! [link] [comments]  |
| How do the joints of a hummingbird deal with all the wear? Posted: 08 Feb 2017 10:25 AM PST I was having a discussion about hummingbirds and one of the questions that came up was how hummingbirds deal with the consequences of the repetitive motion at the shoulder joint. In humans, the repetitive motion quickly wears cartilage down resulting in severely decreased mobility but it doesn't seem that hummingbirds suffer from the same issue. [link] [comments]  |
| Posted: 08 Feb 2017 06:28 AM PST |
| Posted: 08 Feb 2017 01:34 PM PST They're both point particles so... they both have probability clouds? [link] [comments]  |
| What causes some rocks/minerals to naturally form with right angles and straight edges? Posted: 08 Feb 2017 02:53 PM PST I saw a picture of naturally occurring fluorite in a chemistry textbook and wondered why is it naturally forms a near-perfect cube. [link] [comments]  |
| Over what distance does rayleigh scattering have an effect distinguishable by naked eye? Posted: 09 Feb 2017 12:42 AM PST Since blue light is scattered more due to it's wavelength over a certain distance, is red light (from a source about as bright as carbeams) for example visible to further distances relevant on earth or does this only come into account over greater distances? I saw in a video that blue light from an emergency vehicle is only visible up to an altitude of 500m (1640 feet) whereas red light reaches 3 times higher. Is this true? Thanks in advance. [link] [comments]  |
| Why does wood turn "grey" after being outside long enough? Posted: 08 Feb 2017 01:40 PM PST I have seen that newer wood turns into a grey color if it stands outside long enough. I want to know why this happens, and if this happens to other materials. [link] [comments]  |
| How far can a human scream/ howl travel? Posted: 08 Feb 2017 11:23 PM PST I know that howler monkey voices can be heard for miles. But if a human - male or female (on the ground) were to howl in a similar manner, how far would it travel? It would be helpful to know the distance for different landscapes, such as in a forest, in a city, flat farmland, mountains, at sea/ by the coast. Is there a type of landscape/location that is best for reducing the distance the sound could be heard from? And is there an outright best sort of location to hear this voice? How much does weather affect distances? [link] [comments]  |
| Why do some 'old' people look very young for their age? Posted: 08 Feb 2017 11:13 PM PST Let's say the age we're talking about is 65. I've noticed that some people around this age look in their early 50s, others in their early 80s! Is this mostly down to UV/ toxin damage and genetics, or do personality and things like social status and employment make a significant difference? [link] [comments]  |
| What happens to a metal lattice as an EM wave hits it? Posted: 08 Feb 2017 02:24 PM PST So anything you got from EM to Quantum would be nice. What is permeability and permittivity according to perturbation theory? What "losses" occur in a metal lattice and how do you characterize them? What happens to the states of bonds as the wave function changes about them? Anything and everything helps, Thanks! [link] [comments]  |
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