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Homework Help: Conservation of energy/momentum

  1. Mar 22, 2008 #1
    1. The problem statement, all variables and given/known data
    A proton with mass 1.59*10-27 kg is propelled at an initial speed of 3.49*105 m/s directly toward a uranium nucleus 4.97 m away. The proton is repelled by the uranium nucleus with a force of magnitude F = a/x2 where x is the separation between the two objects and a = 2.18 *10-26 Nm2. Assume that the uranium nucleus remains at rest. What is the speed of the proton when it is 8.60 *10-10 m from the nucleus?

    2. Relevant equations

    net force(F)=rate of change of momentum(dP/dt)
    Total Energy before=Total Energy after
    mathematically, E=kinetic energy(KE) before+potential energy(U) before=KE after + U after

    3. The attempt at a solution
    plugging in given values into the equations i think are relevant, but none of them get you any where..IS THERE AN EQUATION IM SUPPOSED TO USE?
  2. jcsd
  3. Mar 22, 2008 #2
    P.S initial speed=3.49*10^5 and so on
  4. Mar 23, 2008 #3
    Use simple Force equations.
  5. Mar 23, 2008 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Find the work done by the force. You'll have to integrate.
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