Recent comments in /f/askscience

rootofallworlds t1_j3207ah wrote

Reply to comment by OverJohn in If an object is placed at the end of of a VERY long bar that is connected to an axel, Could rotating the bar close to the axel make the object at the other move extremely fast (like light speed)? by Swade060504

In classical mechanics, if the stiffness (ie the relevant elastic moduli for the wave type) tends to infinity or the density tends to zero then the speed of sound tends to infinity. Am I correct to think that when you apply special relativity, the speed of sound would tend to c and not infinity in those limits?

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Sharlinator t1_j31zlbj wrote

Reply to comment by train1111818 in How fast would a body fall to earth if there was no atmosphere to stop it from accelerating past a terminal velocity? by straubzilla

If the force that accelerated you were constant, you could indeed reach a speed arbitrarily close to the speed of light just by starting arbitrarily far away – and escape velocity wouldn't be a thing, either.

But gravity is inversely proportional to distance squared, so if you're very far away (in a toy universe where there are only you plus the object you're falling towards), your initial acceleration will also be very slow and almost all of the speed gain will happen when you're already very close to the object.

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S-Markt t1_j31xi2b wrote

Reply to comment by Ausoge in How does dish soap eliminate bacteria? by [deleted]

in addition to that. soapwater encapsules dirt with soapwater so dirt can no longer stick to your skin or sponges and can be washed away. with washing it dirt away you wash away lots of bacteria and one of the main problems with bacteria is: the more are there the more likely it is to be infected. so soap does not only destroy bacteria, it also washes them away.

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Blakut t1_j31swzl wrote

Reply to comment by Ausoge in How does dish soap eliminate bacteria? by [deleted]

then why wasn't it enough to wash wounds with soap to prevent infection before antibiotics? And how come it doesn't dissolve the lipid bilayer around human cells? And what about all the bacteria that live on soap?

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