- #1

- 33

- 0

## Homework Statement

A proton sits at coordinates (x,y) = (0,0), and an electron at (d,h), where d>>h. At time t=0, a uniform electric field

*of unknown magnitude but pointing in the positive y direction is turned on. Assuming that d is large enough that the proton-electron interaction is negligible, the y coordinates of the two particles will be equal (at equal time)*

**E**a) at about y=d/2000;

b)at an undetermined value since

*is unknown;*

**E**c)at about y=d/43;

d)nowhere: they move in opposite directions

## Homework Equations

E=F/q

F=ma

## The Attempt at a Solution

The correct answer is a) but I don't know why. I have no idea how the answer connects d, a x-coordinate, with the final y-coordinate.

This is my attempt::

E=F/q

Since the E is the same and the q is the same, the 2 Forces must be the same

(mass of electron)(acceleration of electron)=(mass of proton)(acceleration of the proton)

(acceleration of electron)=1833(acceleration of proton)

S=(0.5)(acceleration of electron)t^2+(0.5)(acceleration of proton)t^2

of course, S=h-0 or S=h, and (acceleration of electron)=1833(acceleration of proton)

h=(0.5)(1833a(proton))t^2+(0.5)(a(proton))t^2

a(proton)=h/(917t^2)

I have no idea how to go from there...please help

Thanks a lot