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Homework Help: Dimensions of three constants

  1. May 19, 2008 #1
    1. The problem statement, all variables and given/known data

    Consider a Rocket in space, far removed from external gravitational influences, and suppose the engine starts up. As long as the engines are running, its instantaneous velocity v is a function of its mass. V is given by:

    V = A + B log(D/m)

    A, B, D are physical quantities, find the dimensions of A, B and D.

    2. Relevant equations

    V = A + B log(D/m)

    3. The attempt at a solution

    From here I will refer to dimensions as such: [], ex. [V] dimensions of velocity.

    [V] = L/T
    thus [A] = L/T

    I need to still find the and [D]. I am not entirely sure here of how to approach. But would the dimensions of log be nothing, in other words [D] = M or mass.

    and thus = L/T as well. Or it this a stupid assumption to make?

    Thank you for the help.
  2. jcsd
  3. May 19, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Makes sense to me.
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