1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Radium decomposes radioactively

  1. Oct 22, 2012 #1
    Radium decomposes radioactively to form radon (atomic number 86, which is also the number of protons in the nucleus) by emitting an alpha-particle from its nucleus.

    The mass of an alpha-particle is 6.6404 x 10^-24 grams.

    What is the force of repulsion between the radon nucleus and the alpha-particle, when the distance between them is 5 x 10^-11 cm?

    What is the acceleration of the alpha-particle at this distance?

    I am not sure what equation I need to use to solve this equation.

    Any help would be appreciated!
  2. jcsd
  3. Oct 22, 2012 #2


    User Avatar
    Science Advisor

    Try looking up Coulomb's law.
  4. Oct 22, 2012 #3
    Coulomb's law is F = k x ((force1 x force2)/r^2)

    Where k is 8.99 x 10^9

    and r = distance between them which is 5 x 10^-11

    I do not know how to get the force of each particle.

    Some more help would be appreciated!
  5. Oct 22, 2012 #4


    User Avatar
    Science Advisor

    No, that's not Coulomb's law. Coulombs law is
    Force = k x ((charge1 x charge2)/r^2)
  6. Oct 22, 2012 #5
    So i do not know what the alpha-particles charge is, but i can look up radon's charge right?

    So the alpha-particle's charge is the opposite of what radium loses?
    Last edited: Oct 22, 2012
  7. Oct 22, 2012 #6


    User Avatar
    Science Advisor

    Do you know what an alpha particle is? You should be able to look up its charge also.
  8. Oct 22, 2012 #7
    The entire question was in my first post. The difference between radium to radon is 88 -> 86 so would charge 1 be 2 and charge 2 be -2?
  9. Oct 22, 2012 #8


    User Avatar
    Science Advisor

    No. You should know or be able to find:

    (1) What is the charge on a Radon nucleus?
    (2) What is an alpha particle and what is its charge?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook