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# Calculating number density watch

1. I'm doing A-level physics and on the following question I'm not sure about the units

1) Copper has density of 8.9x1029 kgm-3 and a relative atomic mass of 64. Calculate the number density of copper atoms.

I have used N = pNA / M so the equation would be N = 8.9x103 x 6.02x1023 / 64
But I'm pretty sure you have to convert some of the values and I'm unsure which ones, as well as how to
2. Hi,
I'm doing A level physics too but number density calculations (although other no. density stuff is) aren't in my spec. But all of those are base units so it should be ok? Number density is measured with a m^3 but can be measured in a cm^3 too so that might be what you're thinking of about units? Does the question ask for it in a particular unit?
-Clipsi
3. (Original post by Eclipsi)
Hi,
I'm doing A level physics too but number density calculations (although other no. density stuff is) aren't in my spec. But all of those are base units so it should be ok? Number density is measured with a m^3 but can be measured in a cm^3 too so that might be what you're thinking of about units? Does the question ask for it in a particular unit?
-Clipsi
The question doesn't ask for any units so I'm sure it's fine, and the question is an extension question on a homework so I don't think it is on the syllabus. But anyway, thanks for your help

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