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Heisenberg Uncertainty-Which numbers to use? Sig Figs?

Posted: Sat Oct 08, 2016 5:04 pm
by Cowasjee_Sanaea_3E
If a problem tells you (just making up an example) that something with the mass of 10 kg is going at the speed of 3.50 m/s plus or minus .4 m/s, which number would you use to solve the for the momentum? Would delta x be .4 + .4= .8 m/s? And if so, does that mean that in your answer you would only have one sig fig (or do the sig figs still correspond to the 3.50m/s, and in that case have 3)?

Thanks in advance!

Re: Heisenberg Uncertainty-Which numbers to use? Sig Figs?  [ENDORSED]

Posted: Sat Oct 08, 2016 7:11 pm
by Fengting Liang 1F
Delta x is the uncertainty in position so if it's speed (m/s) then I think your value would be delta p (uncertainty in momentum). And you're right, it would be .4+.4=.8. In regards to your sig fig question, I was taught to use the lowest amount of sig figs in my final answer. Like in your example 3.50 has 3 sig figs and .4 has one sig fig, so the final answer should have one sig fig. Hope this helps! :)