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Hitting two objects together

  1. Oct 26, 2004 #1
    why when i hit the desk with my hand do the atoms of the two objects not collide and distrupted the moleculer compound?
     
  2. jcsd
  3. Oct 26, 2004 #2

    Bystander

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    They do. If your question is, "Why don't I see great clouds of smoke, flame, ash, and other detritus?" the answer is that such residue is produced in such small quantities as to be unnoticeable. Calculate the amount of energy you are dissipating when you strike the desk with your hand --- tens of joules. Compare this to the energy required to decompose one mole of water --- ca. 400 kJ. Ask yourself how much water you can decompose --- 10s of micromoles, 100s of micrograms. Is it detectable?
     
  4. Oct 27, 2004 #3
    does the small residue affect ne of the molecules at all?
     
  5. Oct 27, 2004 #4
    What happens is likes repell, and an atom has electrons (negatively charged) hovering aroung it. These electrons orbit the atom so fast, it would look like an electron cloud. The two electron clouds repell each other, so you can not dig into matter, as if it wasn't there.
     
  6. Oct 27, 2004 #5

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    Yes, those it's derived from.
     
  7. Oct 27, 2004 #6

    Claude Bile

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    This is not quite the whole story. In a gas, such forces exist, however you are able to penetrate a gas quite easily. It is the restoring force supplied by the lattice of the solid you are hitting that provides the repulsion.

    Claude.
     
  8. Nov 21, 2004 #7
    Gas can be penetrated, because none of the gas molecules have any covelant bonds. In a desk, there are covelent bonds that make the desk a solid. As the hand presses on the desk, it compresses the atoms of the desk a little bit, it is the restorative force that pushes the desk back in shape. The restorative force is electron clouds repelling each other.

    :cry:
    Double negatives, misspelled words, no "Of."
    Geeze!!!
     
    Last edited: Nov 21, 2004
  9. Nov 24, 2004 #8

    dextercioby

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    Though i don't believe in anything but the force of the human mind,i dare to say:
    "Jesus Christ,where the hell did u read this stuff?"And more:"Why do you think it is correct what you're saying?".
    I honestly believe that your knowledge of (American) English spelling is perfect compared to the one of Physics... :tongue2:
     
  10. Nov 24, 2004 #9
    Where did I read this, almost EVERY physics book in America!!!
     
  11. Nov 24, 2004 #10

    dextercioby

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    1.Your probably ment "covalent bonds".Gas molecules are made mostly of covalent bonds.Yes,at high energies(temperures) the molecules dissociate into constituting atoms.At normal temperatures,the gas state is characterized by strong forces of interraction inside the molecule (the covalent binding is a strong one,compared to metalic or ionic binding) but very weak interraction forces between the molecules themselves,that is because the mean distance between those melecules in the gas state is roughly 10-100 times larger than molecular dimensions.Of course,i assumed simple molecular structures,not the ones stretching over thousands of carbon,hydrogen,oxygen atoms.The potential Lenard-Jones (sounds familiar??) is very fast decaying with the distance between molecules.So,my friend,gas can be penetrated due to the lack of organization (experienced by the liquid and especially the solid states) at molecular level and due to the fact that attracting and repelling forces between its molecules are very weak.
    2.In a desk,probably made of wood,the covalent bindings are indeed strong within the molecular structure,but point 1)does not apply because the molecular size is huge compared to the atomic dimensions (macromolecules can range up to microns) and the forces of interraction between those macromolecules are far larger than before,as i'm talking of thousands of atoms very close to each other not only within the molecules,but also,due to size reasons,very close to the atoms of the surrounding atoms.Trying to apply Lenard-Jones potential would be entirely stupid.
    3.Your last two phrases would marvelously fit into a description of a metal,seen as a crystal lattice with metalic bonds between the atoms.

    Give me some titles for those "intelligent" books you've read.What are electron clouds??
     
    Last edited: Nov 24, 2004
  12. Nov 25, 2004 #11
    ...Okay, you're right. I, actually, recently learned that molecules are not interconnected with covelant bonds. Instead, molecules are interconnected by attractive force between the molecules, right? Anyway, the covelant bonds only bind the atoms in the molecule, not the entire structure. I learned this after I posted the other two posts.
    Electron clouds are electrons. The electrons move so fast, that they make what look like clouds.
     
  13. Dec 6, 2004 #12

    Claude Bile

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    This is incorrect, if it were, electrons would continuously emit radiation. This is experimentally observed not to be the case.

    Bound electrons are more like standing waves than point particles zipping around in space. The standing wave (or orbital) has a distributed mass and charge that does not vary with time, which agrees with the observation that atoms are do not continuously emit radiation.

    Claude.
     
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