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Electric Field Problem in a Tube

  1. Jan 26, 2009 #1
    1. The problem statement, all variables and given/known data
    An alpha particle (a helium nucleus) is traveling along the positive x-axis at 1425 m/s when it enters a cylindrical tube of radius 0.700 m centered on the x-axis. Inside the tube is a uniform electric field of 5.00x10-4 N/C pointing in the negative y-direction. How far does the particle travel before hitting the tube wall? Neglect any gravitational forces. Note: mα = 6.64x10-27 kg; qα = 2e.

    2. Relevant equations
    d(delta)y=v(int)yt + 1/2at^2

    3. The attempt at a solution

    (5x10-4)(2)(1.6x10-19) = F = 1.6 x 10-22
    (1.6 x 10-22)/(6.67 x 10-27) = a = -2.41 x 10-4m/s^2

    d(delta)y=v(int)yt + 1/2at^2
    -.7= 0 + (.5)(-2.41 x 10-4)(t^2)
    t= .007622s

    d(x)= (1425)(.007622s)= 10.86 m

    I'm not sure what I did wrong, but I checked my math twice so I guess it must be something with the process that I took. Please let me know if you can help! Thanks!
  2. jcsd
  3. Jan 26, 2009 #2


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    Just wondering why it's not -2.41 x 104m/s^2
  4. Jan 26, 2009 #3
    It is. I just make stupid mistakes. Thanks! Do you see anything else wrong with the calculations? I think I calculated it with the right number I just typed it into here wrong.
  5. Jan 26, 2009 #4


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    I didn't calculate it out. But now that I did it looks ok for the statement of the problem.

    I got 10.85m carrying more precision, but that shouldn't be the problem.
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