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!

Homework Help: Energy Fluxes of Two Objects

  1. Feb 8, 2012 #1
    1. The problem statement, all variables and given/known data
    Suppose two objects have energy fluxes, f and f + Δf, where
    Δf ≪ f. Derive an approximate expression for the magnitude difference
    Δm between these objects. Your expression should have Δm
    proportional to Δf.

    2. Relevant equations
    Δm = m2 - m1 = 2.5 * log(f1/f2)

    3. The attempt at a solution
    So the issue is that I'm not sure which of these solutions would be the better one to work with. However, I did make an approximation with the one as shown below and I'm not sure if it is quite accurate enough. Any assistance is greatly appreciated.

    Attempt 1: Δm = 2.5 * log(f / f+Δf) = 2.5 * [ log(f) - log (f + Δf)]


    Attempt 2: Δm = 2.5 * log(f+Δf / f) = 2.5 * log(1 + Δf/f) ≈ 2.5*Δf

    The second attempt seems more correct to me but I would feel more confident with a second opinion.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted