Errors in calculations? Achieve homework #19

[Ingrid 14A_2E]

For achieve homework problem #19 I was able to get the first part of the problem correct through the use of deltaofv=h/4pi*M*deltaofX

however once I tried to do it on the bottom part after having substituted into the same equation except this time for the mass I calculated 6.6454x10^-24 as the mass of the helium atom, when inputting it to the function as a whole, I get 6.6153x10^-2 and when inputted to achieve it keep marking it wrong, so I was wondering where I went wrong?

for reference the question asks:

"What is the minimum uncertainty in a helium atom's velocity if the position is known within 1.2A

(6.626x10^-34/(4pi)(6.6421x10^-24(1.2x10^-10)

[606045283]

Hi, so where you went wrong is your calculation of the mass of one helium atom because it is off by a bit. To find the mass of the helium atom here is what you do. First look at its mass provided by the periodic table which is: 4.0026g/mol, and then from this you want to convert it to kg. You do this by multiplying the 4.0026g/mol with 1mol/6.022*10^23 (avogrado's number) and 1kg/1000g. From there you should have the accurate mass of helium atom in kg. Then you should approach the problem in the same way as part 1 except this time the mass being the helium atom mass you just calculated. I hope this helps!