Scientific Methods Answer Sheet

  1. Scientific Notation
    1. Multiply: 3.1 x 107 by 3 x 105


    2. Multiply: 1.496 x 1011 by 5.2


    3. Divide: (6.4 x 106)2 by 6.7 x 10-11


  2. Measurement Errors and Uncertainties
    A. Measurement Errors

    1. Wavelengths:


    2. What is the uncertainty in your answer? That is, how far off (in nm) could your determinations be?


    3. How could you make your answer more precise?


    4. Blue and yellow:

      yellow and red:

      blue and red:

    5. Scale Factor:





    6. If you had a friend measure the distances, would her/his results differ from yours? Why or why not?



    B. How does an "accurate" measurement differ from a "precise" measurement?



    C. Diameters of galaxies:



    1. What criteria did you use when determining each diameter?


    2. In determining the relative distances of these galaxies:
      1. Would it matter if you used a different criterion for measuring each galaxy? Why or why not?


      2. Would it matter if one of your class mates used different criteria than you did? Why or why not?


    3. Distances
      1. Which galaxy is the nearest? Farthest?


      2. How much farther away from us is the farthest galaxy compared to the nearest?


      3. What assumption (stated above) is necessary for you to feel confident your answer is correct?


  3. Statistics

    1. Using a piece of graph paper, plot the magnitude (brightness) of the star against its size.


    2. What is the slope of the line?


    3. Does the equation, y = mx + b seem familiar?


    4. Do you see that for all future measurements, all we need to do is measure the size of the star and use our relationship to find the corresponding magnitude?


  4. Significant Digits
    1. How many significant digits are in the following numbers?
      1. 1.5
      2. 3.5689
      3. 4000
      4. 3.68

    2. Multiply 1.5, 3.5689, 4000, and 3.68. Round your answer to the correct number of significant digits.