Uncertainty Value

[Nick Smith 2H]

When you calculate the uncertainty for either position or momentum, what do you base the number of sig figs on? For example, is the case that Lavelle illustrated during lecture with an electron passing through a series of light sensors, we chose a number for the velocity (10 m/s) and said that delta v (uncertainty in velocity) was equal to 2 m/s and wrote the final answer as this: 10 m/s +/- 1 m/s. My question is, if the value for velocity was something like 23.456 m/s, would the uncertainty carry the same number of sig figs?

[Hana Aflatooni]

Hi Nick!
Yes, I believe you are correct. Base the number of sig figs off of the number that the problem gives you. So, if they give you the value 25.867 m/s for the velocity, I would use the same number of sig figs in the answer. (P.S. The midterms are multiple choice, so use that to your advantage!)

[Michelle Gong]

Yes! I think sig figs carry through to your final answer.

[Kaira Shibata 1E]

Yes, I believe sig find carry over to that part of your answer. For the midterms however, it is multiple choice so that should make it easier perhaps.

[Monse Mata 3D]

Hi Nick, yes, the number of significant figures carries on to your answer. However, our exam questions' possible answers may have less so just make sure you pick the one that is closest or see what the possible answers are and see how many significant figures they have so you know ahead of time.

[Janys Li - 1L]

Hi,
Since you are focusing on the indeterminacy, the degree of accuracy would depend on the sig figs the question gives on the +- value. But if you have 2.1232+-1m/s, the degree of accuracy would be 2.

[Ivan Huang Dis 3B]

the sig figs should carry to the final answer according to the examples Lavelle has done in class

[Jonathan Shyu 3L]

I believe yes, the sig figs would be the same. Also, I believe in general how many sig figs any question uses would be the amount of sig figs your answer should be. As others have stated, the mid term is multiple choice so it should make things easier.