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Homework Help: Quantum mechanics minimum uncertainty

  1. Jun 15, 2008 #1
    URGENT!! quantum mechanics question

    1. The problem statement, all variables and given/known data

    In the lungs there are tiny sacs of air, which are called alveoli. The average diameter of one of these sacs is 0.25nm. Consider an oxygen molecule(mass=5.3x10^-26kg) trapped with a sac. What is the minimum uncertainty in the velocity of this oxygen molecule?

    2. Relevant equations

    I'm not sure what equation I should use...then I'll post what the possible answer is

    3. The attempt at a solution
  2. jcsd
  3. Jun 15, 2008 #2


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    I'm reading a similar section in my physics textbook, and I came across an equation ... in the section for Heisenberg's uncertainty principle.

    [tex]\Delta x \Delta p \geq \frac{h}{2\pi}[/tex], where h is Planck's constant.

    Hope that helps?
  4. Jun 15, 2008 #3
    Hey LHC, thanks for the quick reply :)

    I know that nm=r and kg=m but how would I sub it into the equation you mentioned?
  5. Jun 15, 2008 #4
    x--> uncertainty in particle's position...
    p--> uncertainty in particle's momentum...
  6. Jun 16, 2008 #5


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    Staff Emeritus
    Science Advisor
    Homework Helper

    So the equation will tell you the uncertainty in the momentum. Find that.

    p.s. and watch the units ... use meters, kg, & sec for everything.
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