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Homework Help: Electric Field Velocities from Point A to Point B

  1. Mar 2, 2010 #1
    1. The problem statement, all variables and given/known data

    A proton's speed as it passes point A is 4.90×104 . It follows the trajectory: Point A @ 30V through Point B @-10V. What is the proton's speed at point B?

    2. Relevant equations

    deltaV=deltaK/q
    V=40
    vi=4.9*10^4
    q=1.6*10^-19
    m=1.67*10^-27
    deltaK=1/2mvf^2-1/2mvi^2

    3. The attempt at a solution

    40=(0.5)(1.67*10^-27)(vf^2)-=(0.5)(1.67*10^-27)(4.9*10^4)/1.6*10^-19

    velocity final=8.75*10^4
     
  2. jcsd
  3. Mar 3, 2010 #2

    ehild

    User Avatar
    Homework Helper

    The calculation is easier if you factor the right side of the equation:

    [tex]40=\frac{0.5*1.67\cdot 10^{-27}}{1.6\cdot 10^{-19}}(v^2-(4.9\cdot 10^4)^2)[/tex]

    and then simplify.

    ehild
     
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