Electric fields and acceleration

[eltel2910]

Consider a long horizontal conducting wire with charge density
= 5.70*10^-12 C/m. A proton (mass = 1.67*10^-27 kg) is placed and
released 0.820 m above the wire. What is the magnitude of initial
acceleration of the proton?

My thought is: a=q*E/m

and E is: 2*k*charge density/distance to the proton or 2*8990000000*5.7*10^-12/.820m

but I can't get the right answer, which I know to be: 1.199*10^7.

Any thoughts??

 

[berkeman]

Sounds like you are on the right track, but I don't have my E&M books at home (where I am now). What is the equation that you are using for the electric field from a uniform linear charge distribution?