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Homework Help: Significant figures experiment

  1. Nov 19, 2008 #1
    Hi just a quick question about sig figs. If one was too divide a time such as 21.76s into increments of twenty to find the period of revolution for a centripetal force experiment would the answer be two or four significant figures? also if I multiply a mass such as 2567kg by acceleration due to gravity should my final answer be two significant figures? I am sure the answer to my second question is yes but the first I am not so sure about.
     
  2. jcsd
  3. Nov 19, 2008 #2

    mgb_phys

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    21.76 is 4 sig figures. If you measured say 20 rotations to get this answer then yes, you know the time of one rotation to 4sig figures.

    If you have a mass of 2567kg (again to 4 sig fig) and divide by g=9.81 then you only have 3sig figures in you answer. Or more correctly you have mass of 2567 +- 0.5kg and g=9.81 +- 0.005 so you know g to 1 part in 2000 you would know your answer to 1 part in 2000, ie approx +- 1kg.
    If you used g=9.7 then you have only 2sig figures and an error of 1 part in 100.
     
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