Modulus of Vector

Discussion in 'Homework Help' started by mo2015mo, Oct 21, 2013.

  1. mo2015mo

    Thread Starter Member

    May 9, 2013
    157
    1
    Hello guys,,,

    How is the modulus of E = √(2a^2) for the written E-vector as attached photo ,,
    Is not it should equal = (a) ?? ((by using this identity (cosx)^2+(sinx)^2 = 1 ))
    Or there is any mistake by find it ??
     
  2. WBahn

    Moderator

    Mar 31, 2012
    17,718
    4,788
    What photo?

    So are you saying that the E = √(200a^2) would alos equal (a)?

    What does the parens in (a) mean? Is it different than the parens in (2a^2)? If so, how is someone supposed to tell the difference?
     
  3. mo2015mo

    Thread Starter Member

    May 9, 2013
    157
    1
    this attached photo
     
  4. anhnha

    Active Member

    Apr 19, 2012
    773
    45
    I think you are right. However, I would like to be confirmed by someone.
     
  5. WBahn

    Moderator

    Mar 31, 2012
    17,718
    4,788
    You are correct. You might consider throwing this text book away.

    You basically have the x component is a*cos(θ) and the y component is a*sin(θ). The modulus is the Pythagorean sum of these, so

    |E| = √[ (a*cos(θ))^2 + (a*sin(θ))^2 ]

    |E| = √[ (a^2)[cos(θ)^2 + sin(θ)^2] ]

    |E| = √[ (a^2) ]

    |E| = |a|
     
    anhnha likes this.
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