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Homework Help: Finding the mass of a screw lab.

  1. Nov 20, 2011 #1
    I have been given the masses of 5 cups, each with a different amount of screws inside. I am asked to find the mass of a single screw.

    The cups themselves are all equal in mass and the screws are all equal in mass as well.

    I know you are supposed to subtract the cups from each other to eliminate the mass of the cups and just get the screws masses. I am stuck and I can't seem to grasp the concept of how to solve this! Thanks for help.
  2. jcsd
  3. Nov 20, 2011 #2
    set the mass of one cup to x and mass of one screw to y
    and solve for x and y using quadratic equation/elimination method/substitution method
  4. Nov 20, 2011 #3
    would all the equations be equal to the same value? say a cup was 26.7 grams, what would the equation be?
  5. Nov 20, 2011 #4
    you would have to give me all the info in the question for me to make an equation
  6. Nov 20, 2011 #5
    bottle 1 = 28.70g
    bottle 2 = 32.20g
    bottle 3 = 37.60g
    bottle 4 = 45.80g
    bottle 5 = 60.50g
    Last edited: Nov 20, 2011
  7. Nov 20, 2011 #6
    I am sorry but I can't really come up with an answer
    It would just have infinite solutions with those assumptions you gave me

    all I can say is that subtract the masses to get rid of the mass of cup, and find the common factor (but then it is a decimal in this case)
    the mass of screw cannot be bigger than the common factor
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