Recent comments in /f/askscience

kompootor t1_jdu1n6t wrote

Reply to If there was a hole in the ISS, would everyone get sucked out like in Sci-Fi movies? by hobbitlover

For a spacecraft pressurized at 1 atmosphere, a puncture would cause the nearby air (and anything that it can blow with it) to move surprisingly slowly and gently compared to what's depicted in Hollywood. The correct speed of a fluid being sucked out into space is depicted in season 1 of The Expanse (nsfw gory clip). You can do a back-of-the-envelope calculation of this pretty easily (I forget the exact number) and you'll find that the flow of air is being sucked out is the same regardless of the size of the hole (for a puncture larger than a pinhole and smaller than the entire wall).

Also, the force felt from the vacuum is highest near the puncture -- it's a pressure gradient that quickly feels negligible as one moves inward into the ship -- i.e., as more of the ship's air lies between you and the puncture.

So if you're ever in hand-to-hand combat with a vicious alien xenomorph queen, about to be ripped to shreds, and your last hope is to release the air lock... then it was nice knowing you.

[I'm being exceptionally lazy with this comment -- mixing different quantities in the same description, not bothering to look up further reading for you, etc. -- probably because I know the calculation's somewhere in my notes from the past couple years but I can't find it offhand. At the end of the day though, until I either show the math or show other sources, it all just looks bad.]

36

BeneficialWarrant t1_jdu0rmz wrote

Reply to Why does mild compression lead to paresthesia but not paralysis? by Hola3008

While I don't know the full answer, I can assure you that motor deficit does occur with even mild mixed peripheral nerve compression. Weakness and muscle atrophy is a hallmark sign of nerve entrapment, although I agree that sensory effects often seem more immediately noticeable.

Perhaps unconscious proprioceptive feedback circuits modulate motor tone to compensate for mild weakness and ensure normal posture. Or perhaps somatosensory deficit is more bothersome and therefore more consciously noticeable. Or perhaps it has to do with a difference in fiber physiology or myelination. I'd guess it has more to do with the first 2, and its simply that the body is more consciously aware of sensory deficit while mild motor deficit is handled more unconsciously.

Edit: As another person pointed out, the correct answer is that sensory fibers are conveyed around the periphery and motor towards the center of the nerve. Appreciate the love though. I tried my best.

117

FickleSycophant t1_jdtxf0y wrote

Reply to comment by Constant_Breadfruit in Can elephants canter or gallop? by [deleted]

So the word “gallop” has been around and used to describe the fastest pace of a horse for a long time, but it’s my understanding that we didn’t discover that all four feet were off the ground at the same time until the early days of photography demonstrated it. So it’s hard to believe that the term gallop requires all four feet off the ground when we didn’t even know horses did that until maybe 150 years ago.

Edit: https://www.smithsonianmag.com/smithsonian-institution/how-19th-century-photographer-first-gif-galloping-horse-180970990/

0