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

$\Delta p \Delta x\geq \frac{h}{4\pi }$

Cowasjee_Sanaea_3E
Posts: 27
Joined: Fri Jul 22, 2016 3:00 am

### Heisenberg Uncertainty-Which numbers to use? Sig Figs?

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)?

Fengting Liang 1F
Posts: 23
Joined: Sat Jul 09, 2016 3:00 am

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

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! :)