2
$\begingroup$

While including a data table for a lab report, the guidelines asked to include an uncertainty value for each raw data. In this particular lab where we used slotted masses the masses were already given (such as 50g, 200g, etc.). So while recording the masses into the data table, to how many significant figures should I record the uncertainty and for what reason?

Improve this question
$\endgroup$

2 Answers 2

Reset to default
2
$\begingroup$

In general when you are provided with standard masses, and you are not specifically told what the errors in those masses are, then you would assume the errors are negligible.

That is, you can assume the errors in the masses are small enough that the errors in other measurements will dominate. So you can ignore any errors in the masses when calculating the final errors. But read the lab details carefully to make sure you aren't given error information about the masses.

Improve this answer
$\endgroup$
3
  • $\begingroup$ There isn't really any error information about the masses. In a prior lab report, I did assume the errors were negligible; thus, didn't give any uncertainty value for the masses. However, my points were deducted just because of that. $\endgroup$
    – quant_
    Commented Apr 4, 2019 at 12:31
  • 1
    $\begingroup$ @quant_ in that case I think the only thing you can do is ask the lab instructors what the errors in the masses are. Without that information you're just making up numbers. $\endgroup$
    – John Rennie
    Commented Apr 4, 2019 at 14:37
  • 1
    $\begingroup$ I guess that would be the most rational thing to do. Thanks a lot for the response! $\endgroup$
    – quant_
    Commented Apr 4, 2019 at 15:48
1
$\begingroup$

Yes if there is no error in lab mentioned masses then there will be no need to point out that masses.

If there, it is mention to use the masses by candidate him/her self findings then it is necessary to find out the sigficant figure upto the least count (digits) of the instrument that you are using. i.e. For vernier calliper 0.01cm etc.

Improve this answer
$\endgroup$
1
  • $\begingroup$ Measuring with a vernier calliper to find the dimensions and find the appropriate density of the object would contribute to an error. Ya good idea. $\endgroup$
    – Karthik
    Commented Apr 11, 2019 at 13:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.