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Engineering in Higher Education - significant figures

  1. Dec 26, 2012 #1
    Engineering in Higher Education -- significant figures

    I am currently in my 4th semester.
    It seems that every engineering textbooks I encounter have no regard of significant figures (SF).
    Every problems and examples I encounter are like that. Mostly integers, some have decimal figures, but the answers never pay attention to SF.
    On my first year I was doing Physics where SF is a very important concept but now it has been forgotten.
    How about you all? My textbooks are pretty famous and used worldwide. I wonder if your courses disregard SF too.
  2. jcsd
  3. Dec 26, 2012 #2
    Re: Engineering in Higher Education

    I have also noticed that, but as you go along in your studies you will notice that significant figures are only needed under some circumstances.

    It would help to know whats your branch of engineering but for example, when you calculate the Diameter of a shaft you will need to round it up to some "desired" values that are selected for manufacture if its a tube and you calculate the internal diameter you will round it down.

    Significant digits matter in physical or unit transformation constants and in results that you will use in future calculations and the number of digits that you will use depend on the accuracy of the design ergo the money you have. However even if your books have no regard on SF you should be very aware of how to use them and with practice you will learn when to use them and how many. With time you will find out that there are many things your books don't train you for and you will have to solve.
    Last edited: Dec 26, 2012
  4. Dec 26, 2012 #3


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    Re: Engineering in Higher Education

    Enginneering is not a research science. Errors are not often specifically accounted for because in real life situations, they are difficult to impossible to keep track of. That's part of what safety factors are for. But it does definitely depend on the situation.
    Last edited: Dec 26, 2012
  5. Dec 26, 2012 #4
    Re: Engineering in Higher Education

    Make sure your sig fig is less than or equal to your margin of error.
  6. Dec 28, 2012 #5
    Re: Engineering in Higher Education

    Isn't this what lead to the failure in 10th mission of Space Shuttle disaster?
    Finally Richard Feynman, a physicist, is the one who uncovered the cause of the disaster despite his inexperience with NASA and outer space mission.
    During his investigation he also found out that there were very big unconcern about uncertainty and error.
  7. Dec 30, 2012 #6
    Re: Engineering in Higher Education

    If management had listened to their engineers it wouldn't have happened.
  8. Dec 30, 2012 #7

    jim hardy

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    Re: Engineering in Higher Education

    Indeed the Nova show blamed cold o-rings in the rocket engine's shell, and the decision to "go" when weather was too cold for those o-ring seals.

    Much earlier there was a decision to choose the engine with a segmented shell and o-rings over a one piece engine without them.(Aerojet)

    Such disasters are always result of many little things stacked up like dominoes. I guess that's how the "small things of the earth confound the mighty".
    Last edited: Dec 30, 2012
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