Gravitational Force

[mustang]

Problem 15.
Given: G=6.673*10^-11 N*m^2/kg^2.
If the gavitational force between the electron(9.61*10^-31kg) and the proton (1.59*10^-27kg)in a hydrogen atom is 1.2*10^-47 N,how far apart are the two particles? Answer in units of m. Note: I got 9.197872041*10^-11 by r = sqrt(6.673*10^-11*9.61*10^-31*1.59*10^-27/(1.2*10^-47)). Is the answer correct?

[jcsd]

I think you've rounded up the answer somewhere as using those figures I get 9.217861.. x 10-11 m, how many sig. figs did they ask you for? I'd go for two sig figs as that's what they gave the force to, so the answer would be 9.2 x 10-11 m.