I'm trying to work out why electrons don't crash down into the nucleus using HUP. So if we take 10^-10 meters, the diameter of hydrogen, and use 10^-13 meters as our Δx, the HUP should come out unequal. So I get Δp=10^-35*10^13 or Δp=10^-22 and p=mv, so Δv=10^10 This is where I am confused. I don't know how to think about the Δv. What values do we choose for v final and v initial?