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Homework Help: Answer check / little help

  1. Apr 4, 2004 #1
    A proton traveling at 3E6 m/s enters a region where the electric field has a magnitude of 3E5 N/C. The electric field is uniform and slows the proton's motions.

    a)calculate the distamce the proton will travel before coming to a momentary halt?

    B)Calculate the decel. of the proton and the time for it to trqavel this distance

    F=qE = 1.6E-19 * 3E5 = 4.8E-14 N

    a = F/m 4.8E-14 / 1.67E-31 a = 2.87E13 m/s

    D = Vf^2 - Vi^2 / 2A = 3E6^2 / 2 * 2.87E13 = .157 m

    I am not sure how to do part B or what formula to use

    thanks joe
  2. jcsd
  3. Apr 4, 2004 #2
    Assuming "decel." means deceleration, you already found it in part (a). To find the time it travels before stopping, use this formula:
    [tex]V_t = V_0 + at[/tex]
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