[mperez]

So we did an experiment about weighing 4 pre-1980 and 4 post-1980 pennies. The post-1980 pennies turned out to be heavier than the pre-1980 pennies. The standard deviation of each set was ±0.02.

Then I get asked this question in my lab report and I don't understand what it is asking me to do:

How does the standard deviation calculated from your actual 4 pennies compare with the experimental uncertainty due to the balance (± 0.0001 g per penny)?

The "Experimental uncertainty due to the balance" part throws me off. Does anyone have any idea as to what this is asking me to do?

thanks!!

[Yggdrasil]

The lab equipment that we use to make measurements is never perfect and has only a limited precision.  In the case of your balance, if you had two pennies that differed in weight by less than 0.0001g, then the balance would not be able to tell them apart.  Hence, the balance contributes ± 0.0001 g to the standard deviation of your measurements.  If your standard deviation is equal to or less than that uncertainty, your experimental error can be attributed to the precision (or lack thereof) of the balance.  If not, some other factors contributed to the standard deviation (e.g. deviations in the actual weights of the pennies themselves).