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Matthew's Problem Zone #2

Discussion in 'Nerd Out Zone' started by PsychoticLeprechaun, Feb 18, 2014.

  1. Causeless

    Causeless narcissistic, machiavellian and sadistic

    • Moderator
    Heat doesn't rise towards the axis - if it did, surely fire at the equator would face down due to rotation of the Earth?
  2. PsychoticLeprechaun

    PsychoticLeprechaun Designer & Web Developer

    • Dev Member
    Asimov, you sir have found a rather novel way of explaining it, but you have done so correctly - moreover, in a way that I think is simpler to understand! The way I explain it, is by saying that cold air is denser, and therefore acts in the same way as water does to us - giving the flame buoyancy, such that it is forced in towards the axis by the denser air that is "thrown outwards" to the furthest point from the axis of rotation.

    Well done, and question closed - out of interest, are you a physicist/in college(/university) studying in the field? If so, good man! Physics is a brilliant subject.

    Also, I will endeavour to make the next question much more strenuous, else these are just not going to last long enough each time!
  3. Asimov

    Asimov Festina lente. [#32]

    • Member
    I started really reading in 6th grade. My first books were asimov on astronomy, asimov on physics, asimov on chemistry... etc. That's where I got the nickname. Kept it for 30 years.

    I have had more than my share of college courses in physics but I was going to learn, not to get a degree.
  4. Arpak

    Arpak Moderator - Former CM

    • Moderator
    I think what you mean in english is centrifugal force
  5. Restless

    Restless Terraformer

    • Member
    Can you please explain the answer in a little more detail? I'm just very confused by the answer and can't really picture in my mind how it works.
  6. Asimov

    Asimov Festina lente. [#32]

    • Member
    You've seen a bucket with water in it swung around in a circle at the end of a rope, right? (Or at least can imagine it.)

    Pretend you're on a boat in the bucket. Light a candle. Just like the water is being held in the bucket by rotational forces, so the denser air is being pushed down toward the bottom of the bucket too. The less dense air (like that of the hot air rising off the candle flame) is going "up", but in this case, up is toward the axis.
  7. PsychoticLeprechaun

    PsychoticLeprechaun Designer & Web Developer

    • Dev Member

    Of course! So, when the candle begins to spin, there is a force towards the centre, called the centripetal force which is equal to the mass of the body * the distance from the centre * angular velocity squared. Force being equal to mass * acceleration means that you have an acceleration equal to distance from the centre * angular velocity squared. This acceleration means that, though the flame is at rest relative to the carousel, it has a centrifugal inertial force acting outwards. Inertial forces are proportional to the mass of the body, and as hotter air is less dense, that means that the largest mass - the cold air - must be acted on the greatest and therefore is "thrown" out with greater force. As buoyancy forces act on the flame, as I described before, the flame must therefore tend inwards to allow for the cold air to occupy the furthest locations from the axis of rotation.

    If I made any mistakes, please correct me!
  8. PsychoticLeprechaun

    PsychoticLeprechaun Designer & Web Developer

    • Dev Member
    Well, Asimov, you win the greatest prize of all: pride! It's always great to find other people that equally like physics!
  9. Asimov

    Asimov Festina lente. [#32]

    • Member
    I hope it's your pride and not mine. Hate to be thought of as egotistical. :p
  10. PsychoticLeprechaun

    PsychoticLeprechaun Designer & Web Developer

    • Dev Member
    Haha! Pride isn't egotistical though! It is simply a feel good emotion you get when you achieve something! To be egotistical would be to not feel pride, because one felt that they would definitely get it right before anyone else!

    I will post a new one later today, for now I must do some musing.
  11. Restless

    Restless Terraformer

    • Member
    I didn't understand the first part but this part quoted made it clear for me thank you.
  12. Arctic

    Arctic Giant Robot Advocate

    • Tester
    Changing velocity positively or negatively. Due to relativity, a sealed-off, consistently moving object cannot be blah blah viewpoints.

    If it was accelerating, then it would tend backwards, as the flame would have less velocity than the candle and any newer flames, and air resistance is a none-issue here.

    But it's a circle. So I suppose (Not done ANY research nor am I a physicist) it would tend in a tangent to the circle, or at least an imaginary circle with the candle as its radius, and the center of the carousel as its center, since the flame would want to keep going in that direction, owing to Newton's first law of motion. Therefore, it makes sense the flame would tend outward, as this is where the tangents would be relative to the flame.

    Also, centrifuges work.
  13. PsychoticLeprechaun

    PsychoticLeprechaun Designer & Web Developer

    • Dev Member
    Arctic, indeed that is the case, something must tend outwards due to the fact that it is in a circular motion, however what is denser, cold or hot air? - Which rises? Given that answer, which of the two should tend outwards to a greater extent?
  14. tetryds

    tetryds cus tet, that's it

    • Member
    edit: ops, didn't see this was closed :facepalm
  15. PsychoticLeprechaun

    PsychoticLeprechaun Designer & Web Developer

    • Dev Member
    Indeed, I shall be making another in the next few hours no doubt! I like the way in which these have been received so far, I just wanted to give that one some time for the solution to settle in - it is a very weird effect when one bases physical phenomena on what they see.
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