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Homework Help: Very Simple Question Help Please

  1. Sep 4, 2008 #1
    I know this question must be the easiest thing ever but I can not manage to pick the right choices.I feel really stupid. This is the only question I have left and the homework is due tonight at midnight.
    http://i38.tinypic.com/301d0uf.jpg
     
  2. jcsd
  3. Sep 4, 2008 #2

    LowlyPion

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    What are the units of each of the quantities?

    Is one different?
     
  4. Sep 4, 2008 #3
    Three of them are length units and and 2 of them are mass units. I've picked the three that are length and the two that are mass units and did not answer correctly. Then I eliminated all which were not from the base SI Units and it wasn't the right answer either.
     
  5. Sep 4, 2008 #4

    LowlyPion

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    Now look put the data into a uniform format. Put the mass and length in the same units appropriate each.

    Now look at the results. Remember more than 1 can be in error.
     
  6. Sep 4, 2008 #5
    0.0001 kg
    0.0002 meters
    0.21 kg
    0.004 m
    0.0005 meters
    I would suspect the 0.21 kg and 0.004 m to be incorrect but that's not the right answer. I am not sure if I should look at the rules for uncertainties to answer this question correctly.
     
  7. Sep 4, 2008 #6

    LowlyPion

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    Wait. Those aren't the numbers
     
  8. Sep 4, 2008 #7
    Yeah, somewhat. It's the first homework of the first chapter.
     
  9. Sep 5, 2008 #8

    LowlyPion

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    .0132 kg
    .02365 m
    5.1 kg
    .023 m
    .034 m

    Th kg numbers look quite different.
    The meter numbers look about in the same range.

    However on the basis of significant digits the 5.1 +/- .21 number and the 23.65 +/- .2 has greater error than precision measured. The last number 3.4 +/- .05 looks suspicious because the measurement is less precision than the recorded.
     
  10. Sep 5, 2008 #9
    Ahh!! I didn't get the answer before the deadline. Thanks anyway. I'm going to stop by the teacher's office this weekend.
     
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