# Help with electron in electric field problem!

1. Jan 6, 2010

### Nano

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

An electron has an initial velocity of 5 ×
105 m/s in the x direction. It enters a uni-
form electric field ~E = (440 N/C) ˆj which is
in the y direction.
The charge and mass of an electron are
1.6×10−19 C and 9.11×10−31 kg, respectively.
Find the acceleration of the electron.

2. Relevant equations

F=eq
F=ma

3. The attempt at a solution

I tried using those two equations and coming up with a = Eq/m, but thats not the correct answer!

2. Jan 6, 2010

### Staff: Mentor

That should work just fine. Show what you did.

Since acceleration is a vector, they may want you to specify its direction as well.

3. Jan 6, 2010

### Nano

440 * (1.6e-19)/ (9.11e-31) = 7.2777e13 m/s^2

I'm submitting it into an electronic homework service, which is very picky. I tried submitting a negative answer too, but thats is not correct either....

4. Jan 6, 2010

### Staff: Mentor

Check your arithmetic. (I suspect it's just a typo here.)

Since the directions were given using unit vectors, perhaps that's what they want in the answer.

5. Jan 6, 2010