1. Not finding help here? Sign up for a free 30min 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!

How Do I Solve These Problems?

  1. Oct 17, 2012 #1
    I've memorized all the formulas I need for my first intro to physics class...But I am still trying to get familiar with what formula to use for what problem. Here are two questions. If someone could tell me what formula i would use to solve them, that would be great!!

    1. At what rate does a protostar with a temperature of 2500k radiate most strongly?

    (I'm thinking that we would want to use weins laws that states lambda max is equal to 1/temp. But 1/2500k does not give me a wavelength....)





    2. In a far away galaxy, light is emitted with an average wavelength of 450nm. If this galaxy is moving away from earth at a rate of 1.3*E8 m/s, what wavelength of light will we see?

    (So if its moving away that tells us that it will be a redshift...But how do we get the exact wavelength? I'm thinking that we would divide the recessional velocity of 1.3*E8 by our constant 3*E8, which would give us 2.31m. And then we would say that our

    change in wavelnth/true wavelenght of 450 = to 2.31 m/s

    Am I on the right track here? This gives me 1038, but I'm guessing I need to convert one of these two first. Or maybe I'm doing this completely wrong....)



    P.S.-You people have been awesome with your previous help. I hope that one day I am able to answer peoples questions!
     
  2. jcsd
  3. Oct 17, 2012 #2
    It may be just me, but the question is meaningless. One could ask just at what rate a protostar with a given temperature radiates, but "most strongly" makes this incomprehensible.

    What is the Doppler shift formula?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook