# Homework Help: Electric field accelerated proton

1. Sep 26, 2010

### SixPaperCups

1. The problem statement, all variables and given/known data

The electric field at a point in space is E= (200i+ 900j)N/C .
What is the magnitude of the proton's acceleration?

2. Relevant equations

a = F $$_{on q}$$ / m = (q/m) E

3. The attempt at a solution

I determined earlier that the x-component of the electric force on a proton was Fx = 3.20×10−17 N
Then
I found that the y-component of the electric force on a proton is Fy = 1.44×10−16 N
I know both of these are correct So
I added Fx and Fy together getting 1.76*10^-16
then I divided this net force by the mass of a proton: 1.67x10^-27 kg as the formula above suggest and got 1.05*10^11 as my answer.....it's wrong but I have no idea wrong. Please help

Last edited by a moderator: Sep 26, 2010
2. Sep 26, 2010

### Astronuc

Staff Emeritus
The electric field strength and force are vectors. One does not simply add the magnitudes of the components of a vector to obtain the magnitude of the vector.

http://hyperphysics.phy-astr.gsu.edu/hbase/vect.html#vec4