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Homework Help: How fast are we traveling around the galaxy?

  1. Sep 21, 2006 #1
    heya all, i need some help on a homework question.

    Here is the question--
    We are located about 28000 light-years from the galactic center and we orbit the center once every 230 million years. How fast are we traveling around the galaxy? Give your answer in both km/hr and mi/hr.

    Okay, i know that we are trying to find the Speed.
    So speed = distance/time.

    so, 28000LYR/230 millions years = speed km

    my question is, since i know that 1LYR= 9.5x10^12 km,
    how do i change the 230 million years to km?.... so i can do the problem?

  2. jcsd
  3. Sep 21, 2006 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    Henceforth, post your homework questions in the Homework & coursework subform (this would go in Intro Physics).
    What distance is this? What does it mean when it says we are orbiting the galactic center?

    Read the question again. What are the units for speed that are specified in the question? km is a unit of distance, so it can not be a unit for speed as well. I suggest you go over the chapter on units carefully, to make sure you understand how they work.
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