Deflection of bullet by Earth's magnetic field

[jkulier]

Homework Statement

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?

Homework Equations

radius = mv/qB
theta = arc length/radius

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.

 

[LowlyPion]

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?