Electric fields

Oct 2019
1
0
An electron moving to the right at 0.01c enters a uniform electric field. If the electron is to be brought to
rest in a space of 4.0 cm, what is the direction and strength of the electric field?

I've tried solving using initial energy, the resulting field strength seamed very small, any pointers?

heres a photo of my attempt:

 
Oct 2017
561
282
Glasgow
You forgot to square your speed of light.