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Homework Help: Simple algebra to find the strict mass–energy equivalence formula, and I cant do it

  1. Dec 29, 2012 #1
    Simple algebra to find the strict mass–energy equivalence formula, and I cant do it!!

    find ((m^2)*(c^4)=(E^2)-(p^2*c^2)) from (E=m*c^2*y) (p=m*y*v)
    (y=1/(1-(v^2/c^2))^(1/2))


    Yeh i can find the m^2c^4 parts and the E^2 obvioulsy. but then i am stuck with E^2(v^2/c^2) when instead i want (p^2c^2). If anyone could help that would be great!
     
  2. jcsd
  3. Dec 29, 2012 #2

    Doc Al

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    Staff: Mentor

    Re: Simple algebra to find the strict mass–energy equivalence formula, and I cant do

    Use E=m*c^2*y again.
     
  4. Dec 30, 2012 #3
    Re: Simple algebra to find the strict mass–energy equivalence formula, and I cant do

    That will not solve anything... The formula for the momentum has to be used. I recommend you to start with "p = γmv" and find "v" as a function of "p", then find "γ" as a function of "p" and finaly replace "γ" in "E=γmc2" with what you have found.
     
  5. Dec 30, 2012 #4

    Doc Al

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    Staff: Mentor

    Re: Simple algebra to find the strict mass–energy equivalence formula, and I cant do

    Sure it will. It's the first step:
    -step 1: use the formula for E as I described
    Of course it does. That's the second step:
    -step 2: then rewrite the results in terms of p
     
  6. Dec 30, 2012 #5
    Re: Simple algebra to find the strict mass–energy equivalence formula, and I cant do

    OK, I thought you had say to use the formula for E twice, sorry...
     
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