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Homework Help: Significant figures in seconds to hours calculation

  1. Nov 16, 2011 #1
    SOLVED: Significant figures in seconds to hours calculation

    1. The problem statement, all variables and given/known data
    Not exactly a problem, but if I have minutes/seconds and am changing to hours, how many significant figures are there? For example: 29 minutes 57 seconds =0.499166667 hours needs ? significant figures.

    3. The attempt at a solution
    Well, a second to 1/3600 hours. Therefore, I think I might want to measure to a precision of one ten-thousandth of an hour, or possibly 1/1000 hours. I'm not sure which. I know that the minutes doesn't affect the calculation, and I know that the unit conversion is considered to have infinite sig figs.
    Last edited: Nov 16, 2011
  2. jcsd
  3. Nov 16, 2011 #2


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    Staff: Mentor

    The implication is that the original value is accurate to +/- 1 second. If the converted value is to have a similar level of precision, and 1s = 0.00028 hr, then it looks like you'll want four decimal places and the last place will be taken as +/- 3.
  4. Nov 16, 2011 #3
  5. Nov 17, 2011 #4


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    Staff Emeritus
    Science Advisor
    Homework Helper

    I agree the value is accurate to the nearest 1 second, but would approach it differently. If you convert the 29 minutes 57 seconds to seconds, that's 60ยท29+57 seconds or 1767 seconds. That's 4 significant figures -- which for this problem (0.4991... hours) means to the 4th decimal place in agreement with what gneill said.
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