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jian

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About jian

  • Rank
    Quark

Profile Information

  • Location
    evanston, IL
  • Interests
    find new and interesting things, making some friends
  • College Major/Degree
    B.Eng Materials+physics
  • Favorite Area of Science
    Physics, Math, materials science, chemistry
  • Occupation
    student
  1. are you sure you can explain everything?
  2. polymers are generally called soft materials. Liquid crystal ans biopolymers also are classified soft materials/matter. Their feature is that interaction forces between molecules are quite weak(around kT). They have strong response to the small stimulus. However, there properties are strongly dependent on temperature. Normally, there is a critical temperature at which they undergo soft hard transition. For polymer, that is the glass transition temperature. Magazine " Soft Matter" is the scientific publication concentrated on soft materials. You may check it out.
  3. If you use the concept of entropy, then all the statements are equivalent. There is a site explains the 2nd law quite well. http://www.panspermia.org/seconlaw.htm
  4. why not Hydrogen? It reacts with almost all the elements. Its isotopes have huge amount of atomic energy. It is our hope for the future.
  5. Then I have a question about the intermolecular force in PET. Is there any hydrogen bonding between the PET chains?
  6. Ether has very similar structure as alcohol. Why there is hydrogen bonding in alcohol but not in ether? Oxygen atoms have two lone pairs in both cases.
  7. fingerprint identification is one way. But it seems to be not practical to cause so much just for one brush.
  8. jian

    I'm bored...

    Bored by what? I am a bit bored by study.
  9. I have learnt a module about phase transformation. It states that melting occurs at the melting point because the liquid can always wet its solid,mathematically, it is [math]\gamma_{SV}>\gamma_{SL}+\gamma_{LV}[/math]. I am wondering does it mean that melting can occurs a bit lower than the melting temperature because the interfacial energy also perform as a kind of driving force. In addition, can anyone think a way that make melting starts from inside the solid not the surface?
  10. That is not log rule, is basic rule like a(b+c)=ab+ac. it is true.
  11. jian

    global warming

    It is possible but it is not that easy!
  12. Here, V must increase to keep P and n constant. n is the mole of the air inside the balloon, it cannot be changed as hot air doesn't leak out. With the constant n and larger V, its density is smaller, lighter. I doubt about this statement. What you talk about here is the molar mass, it is rather different with density. If we consider the moist as a mixture of water(liquid) and dry air, apparently, the density of moist air will be larger. I can also explain in your point, 1 mole of dry air occupies much larger volume than 1 mole of water. The differences in volume is much larger than
  13. The air expands as heated becauses the average separation of the gas molecules get larger at higher temperature. Hence, there are less gas molecules per unit volume, that is the reason why the it is lighter or density is smaller. The website is trying to explain the process of the mechanism of vertical motion of atmosphere caused by adiabatic expansion or shrinkage. There are basically two modes: When the air is near the ground, it is heated and it rise up because it is less dense than that of cold air. During the process of rising, it expands more as the pressure is smaller, then it
  14. Maybe you need insert an ammeter in the circuit to get the power which is drawn by the motor. However, you still need to know the efficiency of motor. The simplest way is just read these information from its name plate. Usually, the name plate will specify the normal working voltage, and out power under normal working conditions.. As long as your motor is under normal conditions, the power can be directly read from the name plate. The other way is to conduct a simple experment to calculate the power output like lifting an object with mass m. The gravitational energy gained of the object per
  15. As said by DH, it is good for general knowledge but not for research references. It is constantly changing and the reliability is not good enough to be references for a research paper.
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