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Homework Help: No clear on concept

  1. Sep 20, 2005 #1
    not clear on concept

    Q Two protons are aimed directly toward each other by a cyclotron accelerator with speeds of 1650 km/s, measured relative to the earth. find the maximum electrical force that these protons will exert on each other?
    K_a + -U_a= K_b + U_b and K_a=0, U_b=0
    -U_a=K_b
    K_b= 1/2mv^2
    U_a= (1/(4*pi*epsilon_0)((q*q_0)/r)
    F=qE
    is the radius of the earth r and how do i get the force from potential energy?
     
    Last edited: Sep 20, 2005
  2. jcsd
  3. Sep 20, 2005 #2

    Doc Al

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    Staff: Mentor

    If this is meant to be conservation of energy, rewrite it like this:
    [tex]{KE}_i + U_i = {KE}_f + U_f[/tex]
    where K_i is the initial KE; K_f = 0; U_i = 0; U_f is the electrical potential energy when the protons have momentarily stopped.

    Use this to find the distance of closest approach, where KE = 0. Once you have that distance, use Coulomb's law to find the force.
     
  4. Sep 20, 2005 #3
    is r=((q^2/4*pi*epsilon_0)(1/K_i)
     
  5. Sep 20, 2005 #4

    Doc Al

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    Staff: Mentor

    No. Solve for r by equating the intial KE (of both protons) with the final electric potential energy, which depends on r.
     
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