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Homework Help: Deflection of bullet by Earth's magnetic field

  1. Aug 5, 2008 #1
    1. The problem statement, all variables and given/known data

    A 0.0034kg bullet moves with a speed of 160 m/s perpendicular to the Earth's magnetic field of 5E-5 T. If the bullet has a net charge of 13.5E-9 C, by what distance is it deflected due to the magnetic field after it has traveled 1000m?

    2. Relevant equations

    radius = mv/qB
    theta = arc length/radius

    3. The attempt at a solution

    First, I found the radius of the circle via: r = (mv)/qB = 8.1E11

    Next, I found theta using the arc length of the circle traveled by the bullet divided by the radius of that circle: theta = arc/radius = 1000/8.1E11

    Finally, to find the distance it's deflected, I used the triangle approach: tan(theta) = x/1000

    However, my answer is incorrect. Any ideas would be great,
    thanks in advance.
  2. jcsd
  3. Aug 5, 2008 #2


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    Homework Helper

    Just wondering why you wouldn't apply the Lorentz magnetic force law to identify the acceleration the bullet would be subjected to and than apply that to figure deflection?
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