(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A uniform electric field of magnitude 640 N/C exists between two parallel plates that are 4.00 cm apart. A proton is released from the positive plate at the same instand that an electron is released from the negative plate. Determine the distance from the positive plate that the two pass each other. (Ignore the electrostatic attraction between the proton and electron.)

r = 0.04 m

E = 640 N/C

q_{p}= 1.6 * 10^{-19}C

q_{e}= -1.6 * 10^{-19}C

m_{p}= 1.67 * 10^{-27}kg

m_{e}= 1/1830 * m_{p}

2. Relevant equations

[1] x = x_{0}+ v_{0}+ 1/2*a*t^{2}

[2] F = ma = qE

3. The attempt at a solution

PROTON:

using [2], a = q_{p}*E/m_{p}

subbing into [1], x_{p}= 1/2(q_{p}*E/m_{p})t^{2}

ELECTRON:

x_{e}= r + 1/2(q_{e}*E/m_{e})t^{2}

see when x_{p}= x_{e}

t = [tex]\sqrt{2*r/(E(q_{p}/m_{p}- q_{e}/m_{e}}[/tex]

i get t = 2.67 * 10^{-8}seconds

but when i plug it in for x_{p}i get 2.18*10^{-5}m, whereas x_{e}is 4.00 * 10^{-2}m

they should be equal =S

where did i go wrong? thanks!

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# Homework Help: Uniform electric field moving a proton and electron

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