• Can jet fuel melt steel beams?

    I was wondering for an engineering project.
    I was wondering for an engineering project.
    9 answers · 1 day ago
  • Atheists and religious people, how long have the atoms in my body been around? How long will they be around?

    Best answer: The stuff that makes up the atoms have been around since big bang some 14 billion years ago. Atoms, particularly hydrogen atoms, didn't show up until much later. from those hydrogen atoms you get the formation of stars, the fusion reactions within the early stars created much heavier atoms. When these stars... show more
    Best answer: The stuff that makes up the atoms have been around since big bang some 14 billion years ago. Atoms, particularly hydrogen atoms, didn't show up until much later. from those hydrogen atoms you get the formation of stars, the fusion reactions within the early stars created much heavier atoms. When these stars burned out, they released these heavier elements into space via supernova explosions. So, you are essentially made out of star dust. As for how long will atoms exist? Well, we know that the universe is expanding. that is, the space between you and me the atoms that make up our bodies, and the space between the sub-atomic particles that make up those atoms is expanding. Scientist predict that the universe will either grow cold and dark as everything is stretched apart or it will burn up violently as the fabric of pace is ripped apart.
    18 answers · 4 days ago
  • If E=mC^2. Does that not mean M=E divided by C2? And if so how is it we can t change energy back into matter?

    Best answer: m in E=mc² stands for mass, not matter. It's a bit different. Yes sometimes you can create matter from energy (like in particle accelerators), but more generally you have mass. For example let's take an atom with 1 proton and 1 electron (hydrogen atom) for simplicity. We would expect this atom to have the... show more
    Best answer: m in E=mc² stands for mass, not matter. It's a bit different. Yes sometimes you can create matter from energy (like in particle accelerators), but more generally you have mass.

    For example let's take an atom with 1 proton and 1 electron (hydrogen atom) for simplicity. We would expect this atom to have the mass given by the sum of the masses of the components, so we'd like to say something like: m_H = m_e + m_p with m_H the mass of the atom, m_e the mass of the electron and m_p the mass of the proton. Well, it comes out that it's not quite right, because there's the electron-proton bonding energy that reduces the total mass of the system, so it's more like m_H = m_e + m_p - U_ep with U_ep this energy shared between electron and proton.

    In general anyway mass can become energy in decays or nuclear reactions (fusion and fissions), while particle accelerators tend to do the opposite, to convert a big amount of (kinetic) energy into mass (or even better, new matter to study).
    11 answers · 3 days ago
  • If you have more than one propeller on the same shaft does it increase the amount of thrust from the same power?

    Best answer: it would not add much because the air would already be in motion when it reached the downstream props. The thrust comes from pushing air backward, making the plane go forward. If the air is already moving backward at a rate pretty close to the fastest the prop can make it move, then the thrust value will be a lot... show more
    Best answer: it would not add much because the air would already be in motion when it reached the downstream props. The thrust comes from pushing air backward, making the plane go forward. If the air is already moving backward at a rate pretty close to the fastest the prop can make it move, then the thrust value will be a lot less (less acceleration is possible so less force is attained). There is a minor benefit from the increase in mass that the prop would be able to handle, but that would be secondary. There are a lot of other issues that come into play such as the movement of air is not as a perfect tube with no boundary layer issues, and other such things, but those are secondary to trivial in this general discussion.

    In effect, there is a limit to what can be taken as thrust by moving air. Unless the prop is a very inefficient one, adding a second one down-stream will not be of major benefit, and it will carry a cost. Much better to make the primary prop more efficient.
    5 answers · 1 day ago
  • What exactly is a light year ? Does it mean a year of traveling at light speed? Or is a year in light the measurement? Confused?

    Best answer: A light year is the distance a beam of light would travel in a year
    Best answer: A light year is the distance a beam of light would travel in a year
    9 answers · 4 days ago
  • Do humans emit electro magnetic radiation? if so, what are some cool facts about it?

    Best answer: Yes, humans emit heat as infrared and radiation. while infrared radiation is invisible to human beings it is not invisible to cats and dogs and other animals that hunt at night.. "...36 Amazing Facts about Infrared Radiation 1. Almost half of the energy arriving to the Earth... show more
    Best answer: Yes, humans emit heat as infrared and radiation. while infrared radiation is invisible to human beings it is not invisible to cats and dogs and other animals that hunt at night..

    "...36 Amazing Facts about Infrared Radiation
    1. Almost half of the energy arriving to the Earth from the sun comes as infrared light.

    2. Anything which has a temperature puts out heat or infrared light.

    3. Infra Red waves are also given off by stars, galaxies, lamps, flames and anything else that’s warm – including you...

    ...4. One of the advantages of IR observation is that it can detect objects that are too cool to emit visible light. This has led to the discovery of previously unknown objects such as comets, asteroids and wispy interstellar dust clouds.

    5. Everything has some heat and puts out infrared light. Even things that we think of as being very cold, like an ice cube – put out some heat.

    6. Infrared light can travel through thick smoke, dust or fog, and even some materials.

    7. In firefighting, infrared cameras are being used to locate people or animals in heavy spots and to detect hot spots in forest fires.

    8. Humans, at normal body temperature, radiate most strongly in the infrared at a wavelength of about 10 microns. (A micron is the term commonly used in astronomy for a micrometer or one millionth of a meter.)...".

    http://www.infrared-light-therapy.com/in...



    "...
    9 answers · 4 days ago
  • What is the difference between temperature and thermal energy?

    Best answer: ... temperature is by definition the AVERAGE kinetic energy of the particles in an object but thermal energy is the TOTAL of that energy in an object so you could have a cup of coffee with a high temperature but when you compare the total energy in the cup to the total in a lake at low temperature the lake wins the... show more
    Best answer: ...
    temperature is by definition the AVERAGE kinetic energy of the particles in an object
    but thermal energy is the TOTAL of that energy in an object
    so
    you could have a cup of coffee with a high temperature
    but when you compare the total energy in the cup to the total in a lake at low temperature
    the lake wins the race running away

    it's sort of like density
    you could have a small bit of lead like a bullet with high density
    and compare that to a wooden log
    the log weighs more but has a lower density

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    4 answers · 20 hours ago
  • Why do we believe people who cannot prove there ideas?

    Best answer: Many people lack the critical thinking skills to properly evaluate complex scientific ideas. This is exacerbated by the popular press, which is more interested in sensationalism than nuanced understanding. The most common failure in approaching scientific knowledge is the assumption of absolute truth. ALL of our... show more
    Best answer: Many people lack the critical thinking skills to properly evaluate complex scientific ideas. This is exacerbated by the popular press, which is more interested in sensationalism than nuanced understanding. The most common failure in approaching scientific knowledge is the assumption of absolute truth. ALL of our knowledge, scientific and otherwise, is provisional, based on our limited access to reality and subject to revision as more facts become available.

    When it comes to black holes, fortunately, misapprehension of their nature is not going to have consequences for most of us beyond perhaps exposing our ignorance. Much of Hawking's work on black hole theory remains hypothetical, but their existence and certain aspects of their behavior have been observed. How else, for example, would you explain Sagittarius A*? Besides clear evidence of supermassive black holes in galactic centers, there are a number of observable stars in our galaxy in orbit with what appear likely to be black holes.

    As to why we follow this regardless of our ability to evaluate or even comprehend, I think it's because the idea feeds our sense of wonder.
    12 answers · 5 days ago
  • Is Michio Kaku insane?

    Best answer: Well he’s up there in age and probably thinking about his mortality.
    Best answer: Well he’s up there in age and probably thinking about his mortality.
    4 answers · 24 hours ago