Engineering in Higher Education - significant figures

In summary, the Space Shuttle disaster was caused by a number of little things that were stacked up. Management ignored warnings from their engineers, and the result was a disaster.
  • #1
e.pramudita
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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.
 
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  • #2


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 what's 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.
 
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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.
 
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Make sure your sig fig is less than or equal to your margin of error.
 
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russ_watters said:
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.

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.
 
  • #6


e.pramudita said:
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.

If management had listened to their engineers it wouldn't have happened.
 
  • #7


If management had listened to their engineers it wouldn't have happened.

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)
http://history.nasa.gov/rogersrep/v1ch6.htm

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".
 
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1. What are significant figures and why are they important in engineering?

Significant figures refer to the number of digits in a numerical value that are considered to be accurate and relevant. In engineering, significant figures are important because they help to maintain precision and accuracy in calculations and measurements. They also help to communicate the uncertainty in a given value.

2. How are significant figures determined in engineering calculations?

The rule for determining significant figures in engineering calculations is to count all the digits from the first non-zero digit from the left to the right. The last digit in the number is considered to be uncertain or estimated. For example, in the number 3.45, there are two significant figures.

3. What happens when you multiply or divide numbers with different significant figures?

When multiplying or dividing numbers with different significant figures, the final answer should have the same number of significant figures as the value with the least number of significant figures. This is because the accuracy of the final answer is limited by the least precise value used in the calculation.

4. Can you round off significant figures in engineering calculations?

Yes, rounding off significant figures is allowed in engineering calculations, but it should be done carefully to maintain accuracy. When rounding off, the final answer should have the same number of significant figures as the value with the least number of significant figures.

5. How do significant figures affect the reporting of experimental data in engineering?

In engineering, it is important to report experimental data with the correct number of significant figures to reflect the precision and accuracy of the measurement. Reporting too many or too few significant figures can lead to errors and misinterpretation of the data. Additionally, significant figures can also help to determine the uncertainty or margin of error in the experimental results.

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