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Centripetal Acceleration ?

  1. Apr 27, 2009 #1
    1. The problem statement, all variables and given/known data

    The mass of an electron is 9 x 10-31 kg. The mass of a proton is 1.7 x 10-27 kg. The proton and electron are about 1.0 x 10-10 m apart in a hydrogen atom. What force of gravitation exists between the proton and the electron of a hydrogen atom? What is the centripetal acceleration of the electron?

    2. Relevant equations
    Fg = G*m1*m2/d^2
    * Fg is the magnitude of the gravitational force between the two point masses,
    * G is the gravitational constant,
    * m1 is the mass of the first point mass,
    * m2 is the mass of the second point mass,
    * r is the distance between the two point masses.

    ar = v2 / r

    ar is centripetal acceleration
    v is velocity in meters per second,
    r is the radius of the circle in meters

    3. The attempt at a solution

    I plugged in the infomation to find the gravitational force and got 1.02051 x 10^-47
    but it doesn't give us the nessicary information to find the centripetal acceleration... I don't think.. can anyone help me with this?
     
  2. jcsd
  3. Apr 27, 2009 #2

    Doc Al

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    What provides the centripetal force?
     
  4. Apr 27, 2009 #3
    It rotating around the hydrogen atom I think...
     
  5. Apr 27, 2009 #4

    Doc Al

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    The electron "orbits" the proton. Again, what provides the centripetal force?
     
  6. Apr 27, 2009 #5
    I suppose im not sure what you mean.. or what provides it... that is all the question said...
     
  7. Apr 27, 2009 #6

    Doc Al

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    What force holds the atom together? (It's not gravity.)
     
  8. Apr 27, 2009 #7
    The electrical charge of the atom?
     
  9. Apr 27, 2009 #8

    Doc Al

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    Right. The electric force provides the centripetal force. How much is the electrical force? (Hint: Coulomb's law) Once you have the centripetal force, use Newton's 2nd law to find the acceleration.
     
  10. Apr 27, 2009 #9
    5.508 x 10^-27 N is what i got when i plugged it in...
    and for the acceleration i got 6120 meter/second^2
     
    Last edited: Apr 27, 2009
  11. Apr 28, 2009 #10

    Doc Al

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    Please show how you made those calculations.
     
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