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Homework Help: Electron moving between 2 charged plates

  1. Sep 5, 2010 #1
    1. The problem statement, all variables and given/known data
    at some instant the velocity components of an electron moving between two charged parallel plates are vx = 1.20 105 m/s and vy = 3.70 103 m/s. Suppose that the electric field between the plates is given by Evec = (120 N/C) jhat.

    (a) What is the electron's acceleration in the field?
    -2.11*E13 m/s2 jhat Incorrect

    (b) What is the electron's velocity when its x coordinate has changed by 1.4 cm?
    1.20*E5 m/s ihat + -2.46*E6 m/s jhat Incorrect


    2. Relevant equations
    F=ma
    F=E*Q
    V*T=D
    V_0+A*T=V_1
    3. The attempt at a solution
    Rearranging the above equations i get A=(E*Q)/M

    so A=(120*1.6*10^-19)/(9.1*10^-31)=2.11*10^13 jhat in the negative direction

    Because acceleration is in the J direction there is no Iforce, so I is constant. so for D=t*V or t=d/v t=.014m/1.2*10^5=1.17*10^-7

    then V_F=V_I+A*T so V_F=3.7*10^3+-2.11*10^13*1.17^10^-7=-2.46*10^6

    Yet all of my answers are incorrect, what am i doing wrong?
     
  2. jcsd
  3. Sep 5, 2010 #2
    Never mind, my answer was correct but the system wasn't accepting the format i was inputting it as(which is ironically the format they fed the information to me in)
     
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