Solver the all parts of following question given below:
Question: A galaxy known to be traveling away from the Earth at 0.740 percent of the speed of light is observed on Earth to have a strong peak in its spectrum at 640.0 nm. However, one small portion of the galaxy (a "dwarf") has a similar observed peak with a wavelength that is 4.06 nm shorter.
Part I: Calculate the wavelength of the light emitted by the bulk of the galaxy
Part II: What is the speed of the dwarf, relative to its "parent" galaxy? (Enter your answer as negative if the dwarf is moving toward Earth relative to the rest of the galaxy.)
I've been having quite a bit of trouble understanding this question, Thank You so much for your help. Thanks.