• How fast can MRI produce an image?

    I have already been on MRI, and I know it is kind of slow. I want to know, is there any specific reason for that? Is machine physically incapable of working any faster. Or is it maybe too expensive to make it faster? And if we made it as fast as we can, how many pictures could it take per second? Would it be possible to see through MRI scan in real... show more
    I have already been on MRI, and I know it is kind of slow. I want to know, is there any specific reason for that? Is machine physically incapable of working any faster. Or is it maybe too expensive to make it faster? And if we made it as fast as we can, how many pictures could it take per second? Would it be possible to see through MRI scan in real time like a little movie?
    Medicine · 1 week ago
  • My android phone USB connection with computer stops working when phone screen turns off?

    How do I fix this? I can connect my phone to computer via USB and but the moment screen turns off, computer ceases to recognize USB connection.
    How do I fix this? I can connect my phone to computer via USB and but the moment screen turns off, computer ceases to recognize USB connection.
    1 answer · Software · 2 weeks ago
  • How do people make money from shares or stocks?

    My understanding is that you pay plenty of money now and get money from company profits later every month or maybe every year. Is that how it works? Also, how much money is that? Say you buy 1000$ worth of stocks, how much money can you expect to get monthly (or yearly) from that investment if company stock prices don't change?
    My understanding is that you pay plenty of money now and get money from company profits later every month or maybe every year. Is that how it works? Also, how much money is that? Say you buy 1000$ worth of stocks, how much money can you expect to get monthly (or yearly) from that investment if company stock prices don't change?
    4 answers · Investing · 3 weeks ago
  • Why do spiral bacteria exist?

    What kind of evolutionary pressure would cause bacteria to coil up? Or in other words, what sort of benefit would spiral shape give to bacteria?
    What kind of evolutionary pressure would cause bacteria to coil up? Or in other words, what sort of benefit would spiral shape give to bacteria?
    1 answer · Biology · 2 months ago
  • How do trees transport oxygen?

    I know that we have blood which contains hemoglobin to which oxygen binds. But trees and other plants don't have hemoglobin. So how do they do it?
    I know that we have blood which contains hemoglobin to which oxygen binds. But trees and other plants don't have hemoglobin. So how do they do it?
    4 answers · Biology · 5 months ago
  • How do we know protons and neutrons are both composed of 3 quarks?

    Since protons and neutrons are way too small to be observed directly, and quarks have never been isolated as free particles, what experimental data did we use to learn that protons and neutrons are composed of 3 quarks (and not some other arbitrary number)?
    Since protons and neutrons are way too small to be observed directly, and quarks have never been isolated as free particles, what experimental data did we use to learn that protons and neutrons are composed of 3 quarks (and not some other arbitrary number)?
    3 answers · Physics · 5 months ago
  • How do we know the charge of quarks?

    I understand that quarks were never isolated from nucleus, which means we never could test their charge by using electric fields or magnetic fields. So how do we know electrical charge of quarks?
    I understand that quarks were never isolated from nucleus, which means we never could test their charge by using electric fields or magnetic fields. So how do we know electrical charge of quarks?
    2 answers · Physics · 5 months ago
  • What causes cavitation?

    In plumbing and propeller design, what actually causes cavitation, and what are common methods of preventing or avoiding it?
    In plumbing and propeller design, what actually causes cavitation, and what are common methods of preventing or avoiding it?
    3 answers · Engineering · 5 months ago
  • Why do kangaroos fight people?

    9 answers · Zoology · 6 months ago
  • What happens to civilians when their country is occupied?

    There has been many military conflicts throughout history, so I was wondering is there some commonly accepted rule for what happens to civilians of occupied country. Do they become citizens of occupying nation, or are they considered like refugees? Or have less rights or something inbetween? Also, is there a difference between civilians in occupied... show more
    There has been many military conflicts throughout history, so I was wondering is there some commonly accepted rule for what happens to civilians of occupied country. Do they become citizens of occupying nation, or are they considered like refugees? Or have less rights or something inbetween? Also, is there a difference between civilians in occupied territory and civilians when their entire nation is capitulated?
    6 answers · Military · 6 months ago
  • How do we know shape of atomic orbitals?

    I know there are drawings and illustrations of atomic orbitals, but are they directly observed or merely a mathematical approximation based on what we know?
    I know there are drawings and illustrations of atomic orbitals, but are they directly observed or merely a mathematical approximation based on what we know?
    1 answer · Physics · 6 months ago
  • Are commercial laser pointers real lasers or just focused beams of light?

    I understand that for something to be considered a laser, it must have coherent and monochromatic light. So with that in mind, are commercial laser pointers true lasers or are they just small light emitting diodes with lens that makes them look like lasers?
    I understand that for something to be considered a laser, it must have coherent and monochromatic light. So with that in mind, are commercial laser pointers true lasers or are they just small light emitting diodes with lens that makes them look like lasers?
    7 answers · Physics · 7 months ago
  • When x-rays or gamma rays are absorbed, is number of photons reduced or do photons loose part of their energy (and get higher in wavelength)?

    So, to give example let's assume we have a block of lead exactly the half value thickness. And let's say there is 100 x-rays going towards that block. My question is, after passing through the block, is beam of 100 x-ray photons going to be reduced to 50 x-ray photons of same wavelength, or is number of photons going to remain relatively... show more
    So, to give example let's assume we have a block of lead exactly the half value thickness. And let's say there is 100 x-rays going towards that block. My question is, after passing through the block, is beam of 100 x-ray photons going to be reduced to 50 x-ray photons of same wavelength, or is number of photons going to remain relatively unaffected, but their collective energy half of the starting energy?
    2 answers · Physics · 7 months ago
  • Why are there differences between DNA and RNA?

    DNA has thymine instead of uracil like RNA has. And DNA has deoxygenated sugar in it's backbone while RNA doesn't. My question is, is there any advantage to these differences or are they just random?
    DNA has thymine instead of uracil like RNA has. And DNA has deoxygenated sugar in it's backbone while RNA doesn't. My question is, is there any advantage to these differences or are they just random?
    Biology · 7 months ago
  • Cells burst under osmotic pressure but can it not be avoided by blocking water channel proteins?

    I know that cells burst under hypotonic conditions and shrink by forcing water out of cells in hypertonic solution. But, as I understand, water generally only enters cells through water proteins on the cell membrane. Can't cells just plug that protein so it can't pass any more water through it to avoid gaining or loosing too much water when... show more
    I know that cells burst under hypotonic conditions and shrink by forcing water out of cells in hypertonic solution. But, as I understand, water generally only enters cells through water proteins on the cell membrane. Can't cells just plug that protein so it can't pass any more water through it to avoid gaining or loosing too much water when they are in osmotic intense conditions?
    Biology · 7 months ago
  • How do we know the structure of the virus?

    How do we measure shape of viruses when viruses are significantly smaller than wavelength of light? So since we can't use optical microscopes to see how virus looks like, what instrument do we use to see them?
    How do we measure shape of viruses when viruses are significantly smaller than wavelength of light? So since we can't use optical microscopes to see how virus looks like, what instrument do we use to see them?
    5 answers · Biology · 7 months ago
  • What is the efficiency of water electrolysis at 12V?

    Let's say we use NaOH as electrolyte and some unreactive metal for electrodes.
    Let's say we use NaOH as electrolyte and some unreactive metal for electrodes.
    1 answer · Chemistry · 7 months ago
  • Electrolysis voltage vs efficiency?

    What is the relation between voltage applied over electrolysis cell and it's efficiency? I know that more voltage = more current, but at what point is it no longer desirable to increase voltage? Or is there equation of efficiency vs voltage in electrolytic cell?
    What is the relation between voltage applied over electrolysis cell and it's efficiency? I know that more voltage = more current, but at what point is it no longer desirable to increase voltage? Or is there equation of efficiency vs voltage in electrolytic cell?
    2 answers · Chemistry · 8 months ago
  • How public and private keys work?

    I understand the basics. Public key can be used to encrypt data, but only private key can be used to decrypt it. How is this possible? How can message be encrypted using public key and not be decrypted using that same key? And how can a private key be used to decrypt message that was not encrypted using different key? People often use many... show more
    I understand the basics. Public key can be used to encrypt data, but only private key can be used to decrypt it. How is this possible? How can message be encrypted using public key and not be decrypted using that same key? And how can a private key be used to decrypt message that was not encrypted using different key? People often use many analogies, but I am interested in how this mathematically even makes sense. People say mathematics of this encryption system is too complex, but please try not to oversimplify too much. I will try to understand.
    3 answers · Security · 9 months ago
  • What is neutron initiator?

    In nuclear weapons design, specifically implosion type, at the center of the bomb, there is something called neutron initiator. https://upload.wikimedia.org/wikipedia/commons/thumb/e/ef/Implosion_Nuclear_weapon.svg/2000px-Implosion_Nuclear_weapon.svg.png It is, as I understand, a type of material that releases lots of neutrons on demand to kickstart... show more
    In nuclear weapons design, specifically implosion type, at the center of the bomb, there is something called neutron initiator. https://upload.wikimedia.org/wikipedia/c... It is, as I understand, a type of material that releases lots of neutrons on demand to kickstart chain reaction. Is that right? And if so, how do these materials work and what is the mechanism behind their functionality?
    3 answers · Physics · 9 months ago