Why is gold used on connector ends, like on usb-connectors for gaming mice, when copper has lower electrical resistivity? |
- Why is gold used on connector ends, like on usb-connectors for gaming mice, when copper has lower electrical resistivity?
- What is the estimated depth of the liquid water oceans on Titan?
- Can a diurnal predatory species evolve to become nocturnal if their prey is nocturnal? And vice versa? And can it shift back in the other way?
- Are there any examples of food ingredients used today which were first recognized and regulated as drugs?
- Lysosomes - are they more specialized than what I am led to believe in basic physiology lectures?
- Can a storm go in a circle or go backward and hit the same place twice?
- Why do all the planets with substantial axial tilt have such similar angles (besides Uranus)?
- Why when glancing colored led lights sometimes you can see the discrete colors?
- How do European cosmetic industries develop new products without animal testing?
- Are different metals usually found together in mineral deposits?
- Why do Newton's Law of Universal Gravitation and Coulomb's Law of electrostatics look nearly identical?
- In a refrigerator, do a number of water bottles (say 20) cool faster when touching in a square grid or when separated by air?
- How are (high-precision) elevation/hight measurements done?
- How does Trans-cranial magnetic stimulation(TMS) work?
- Can we store information in black holes ?
- Do partially torn ligaments/tendons ever fully heal?
- Where does food go when it “goes down the wrong pipe”?
- If metals consist of positive ion cores surrounded by delocalised electrons, with no discrete bonds to make/break, why don't metals stick together when you touch them to eachother?
- How and when do bacteria in our guts get in there?
- Can lactose dissacharides form polymers?
| Posted: 23 May 2019 04:15 AM PDT I'm reading about electrical components and a table in my book describes "Resistivities of common conductors". Here ideal resistance is described by: Resistance = rho (material resistivity) * L (length of wire) / A (area of cross section of wire) With unit [10^(-8) Ohm meters] copper is cited as having a value of 1.7 where as gold has a value of 2.4. Is the principle of gold connectors just a marketing hoax? [link] [comments]  |
| What is the estimated depth of the liquid water oceans on Titan? Posted: 23 May 2019 02:14 AM PDT Seeing that Titan is thought to have a lot more water compared to earth, what would the estimated depth of the water oceans on Titan be? And bonus question, where does all this water cone from? [link] [comments]  |
| Posted: 22 May 2019 04:09 PM PDT Let's say there's an island with hawks who are active during the day; rabbits who are active during the day, and raccoons who are active during the night. Hawks eat rabbits and raccoons. Slowly, due to some unrelated factor like disease, the rabbit population starts to diminish, so raccoons become an increasingly important food source for the hawks. Over time, can the hawks evolve new behaviors and physical features to make them better at night hunting so they can catch more raccoons? Let's say hundreds of generations have gone by and the hawks have evolved owl-like senses and nocturnal patterns to get really good at catching raccoons in the dark. Could the raccoons then start adapting their behavior and/or physiology to become more active during the day and less likely to be eaten by these formidable night-hawks? [link] [comments]  |
| Posted: 22 May 2019 05:14 PM PDT I had a colleague assert to me that it would be impossible to gain regulatory approval for a food ingredient, used at any concentration, which has a history of use as a drug. This doesn't sound correct to me, but I could not think of any falsifying examples. I have thought of examples in the other direction, like vitamin D supplements vs the prescription, concentrated vitamin D caps, or fish oil vs the concentrate sold as Omacor or Lovasa for lipid lowering. But in both of those cases the low-concentration food ingredient came first. Has it ever gone the other way? Could it? [link] [comments]  |
| Lysosomes - are they more specialized than what I am led to believe in basic physiology lectures? Posted: 23 May 2019 07:57 AM PDT hi! there have been several different times when I came up with a version of the same question: how do lysosomes "know" what to digest? example to illustrate what I mean:
basically - we're taught that lysosomes are these enzyme-filled bags that just digest anything they come across, but that seems very simplistic, and I am curious to know more about their heterogeneity! [link] [comments]  |
| Can a storm go in a circle or go backward and hit the same place twice? Posted: 23 May 2019 07:57 AM PDT |
| Why do all the planets with substantial axial tilt have such similar angles (besides Uranus)? Posted: 23 May 2019 07:54 AM PDT I was flipping through recent NASA APOD posts, and came across this one depicting the solar system planets along with some of their characteristics, including axial tilt. I noticed that all the planets with major axial tilt besides Uranus are all quite similar in angle, between 23 and 29 degrees. Are there any solid theories as to why this is? [link] [comments]  |
| Why when glancing colored led lights sometimes you can see the discrete colors? Posted: 23 May 2019 06:15 AM PDT With some projectors too. Sometimes when I glance at these color changing led lights I can see the discreet RGB colors? Do they flicker at different times? or is it the eye persistence of vision resolving this flicker? [link] [comments]  |
| How do European cosmetic industries develop new products without animal testing? Posted: 23 May 2019 06:07 AM PDT Animal testing for cosmetic products is banned in Europe. On this subreddit I've read that there aren't any real alternatives though and also read surveys that show the vast majority of experts think animal testing is necessary. How do European cosmetic industries develop new products then? Are they just implementing old formulas without any real breakthrough? Has this ban put an end to any further technological development in the industry? [link] [comments]  |
| Are different metals usually found together in mineral deposits? Posted: 23 May 2019 05:46 AM PDT Are different metals found together in mineral deposits? And if so, are there metels more likely to be found together? [link] [comments]  |
| Posted: 23 May 2019 05:36 AM PDT For those unfamiliar, here is Coulomb's Law that governs electrostatics and this is Newton's Law of Universal Gravitation. Both laws state that the force experienced by an object under the influence of the field is equal to the product of the determining property (either mass or charge) multiplied by a constant, and divided by the square of the distance between them. Obviously there are differences. The gravitational constant (G) is very small, while the electrostatic constant (k) is very large, but essentially the equations are mirrors of each other. Swap charge with mass and change the value of the constant and Coulomb's Law becomes Newton's Law and vice versa. I know both gravity and electrostatic force are field properties, so I'm guessing that might be why they look so similar, but I was wondering if this is a simple explanation (like they both happen to function as an inverse square, thus the equations are like convergent evolution) or if it hints at some fundamental similarity in origin between gravity and charge. My knowledge in modern physics as far as quantum and string theory aren't strong enough to draw any conclusions. [link] [comments]  |
| Posted: 23 May 2019 04:43 AM PDT I drink a lot of water bottles (not because the internet said the 8x8 rule, that's dumb) so I'm constantly putting bottles in my fridges; the problem is that they don't get cold immediately (obviously), so how should I position them to cool the quickest? Buffered by air? Square grid? If grids are better surely Honeycomb grids are even better. Should the gridded bottles be standing? Or parallel to the ground like a wine bottle shelf? Very interested in how this is calculated as well. Edit: Physics I guess? [link] [comments]  |
| How are (high-precision) elevation/hight measurements done? Posted: 23 May 2019 03:38 AM PDT The question should cover it, just to make sure/clarify: I'm not talking about a known/created "zero" point and a second unknown point. These delta's are, relatively, easy to calculate and can be very accurate with sensitive equipment. Examples of what I do mean:
How is this determined, in relation to what and how accurate can we be (and does this even make sense)? Especially the last part has been bothering me. Earth is a "living and breathing" thing; Tectonic plates, an active core, a radius of 6371.0 km (3958.8 mi) [equatorial 6378.1 km (3963.2 mi)] etc. etc. Which makes a known fixed point all but impossible(???) and if so all other measurements are approximations at best. I know that in real life and regarding my phone it is irrelevant if I'm -14m or -14.36m or -13.82 below sea level. But 8844.43m seems awfully specific.... And 'real life' is besides the point in this case. And all this because I saw a land surveyor at work. Sigh...... [link] [comments]  |
| How does Trans-cranial magnetic stimulation(TMS) work? Posted: 23 May 2019 02:58 AM PDT I read about TMS in a neuroanatomy book and am under the impression that it basically works by the principle of electromagnetic induction and this is exactly what I cannot seem to understand. For an electric potential to be induced there are two requirements- 1) Changing magnetic fields and 2) There should be a conductor present in these changing magnetic fields for electrical potential to be induced. How is the brain tissue a conductor? I mean of course brain is electrically active but that is due to the exchange of ions as far as I know and neurons mostly work in two mode inhibitory and excitatory states, how does TMS affect this in any significant way and bring about the effects mentioned in the book? [link] [comments]  |
| Can we store information in black holes ? Posted: 22 May 2019 10:49 PM PDT Let me explain myself: for an outsider perspective something falling into a blackhole will seem to be going slower and slower while reaching the event horizon, and we never will see the object disappear into the black hole. Therefore, would it be possible to send objects that carries visual information? Like for example leaving messages for civilization far beyond us ? [link] [comments]  |
| Do partially torn ligaments/tendons ever fully heal? Posted: 22 May 2019 10:46 PM PDT I've partially torn my pec tendon doing bench press over the years. These seemed to me to be somewhat minor injuries since I would recover within a few weeks and there was no bruising around the tendon. Do these types of injuries ever fully heal? Or will that tendon be forever weaker than it could've been? [link] [comments]  |
| Where does food go when it “goes down the wrong pipe”? Posted: 22 May 2019 11:48 AM PDT |
| Posted: 22 May 2019 05:07 AM PDT |
| How and when do bacteria in our guts get in there? Posted: 22 May 2019 08:24 AM PDT It is obvious that bacteria cannot exist in our guts congenitally; therefore there should be a natural mechanism that puts them in our guts. Is it basically our diet or something intricate? [link] [comments]  |
| Can lactose dissacharides form polymers? Posted: 22 May 2019 08:48 AM PDT Lactose is a reducing sugar, but I have never heard of a oligomer of lactose. Potentially the glucose could react with another monomer of galactose, and the galactose again with a glucose etc etc. I know that polymers are generally regarded as repeating monomers, like cellulose and galactan for the monomers in lactose. I am just wondering whether polymers of alternating monomers would be feasible, and if yes, why do they not exist? [link] [comments]  |
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