1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Wavelength with P/Q exponent equation-solve for P/Q

  1. Jan 18, 2010 #1
    1. The problem statement, all variables and given/known data
    Speed of an ocean wave depends on the wavelength [tex]\lambda[/tex] in meters and
    gravitational field. (see equation below). Find values of P and Q. K is a constant and has no dimensions


    2. Relevant equations

    V = K[tex]\lambda[/tex]PgQ

    3. The attempt at a solution

    V=velocity, which is m/s
    and i can disregard K because it is a constant which has no dimensions.
    g = m/s2
    [tex]\lambda[/tex] = m
    plugging in the numbers; i get:

    m/s = mP(m/s2)Q

    here is where i get lost. i dont know how to bring the exponents down so i can solve for it
     
  2. jcsd
  3. Jan 18, 2010 #2

    Mark44

    Staff: Mentor

    You have V = K LPgQ
    (I used L in place of lambda.)
    So LP = V/[K gQ]

    To solve for P, take the log of both sides, then divide both sides by log L.

    To solve for the other exponent Q, first solve for gQ in a way similar to how I solved for LP, then take the log of both sides, and divide both sides by log g.
     
  4. Jan 18, 2010 #3
    are you sure? i was workin on this with my prof and he told me not to take the log; thats what i thought of doing initially
    and i have no numerical values for the equations; its all dimension analysis
     
  5. Jan 18, 2010 #4

    Mark44

    Staff: Mentor

    OK, what's the exact statement of the problem? As you have it in post 1, it appears that you need to solve for P and Q.
     
  6. Jan 18, 2010 #5
    The speed of ocean waves depend on their wavelength [tex]\Lambda[/tex] (measured in meters) and the gravitational field strength g (measured in m/s^2) in this way:

    v = [tex]\Lambda[/tex]PgQ

    where K is a dimensionless constant. Find the values of the exponents P and Q
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Wavelength with P/Q exponent equation-solve for P/Q
Loading...