# Grade 12 Centripetal Acceleration Question- Universal Law of Gravitation

#### AudenCalbray

1. The problem statement, all variables and given/known data
In the Bohr model of the hydrogen atom, the electron revolves around the nucleus. If the radius of the orbit is 5.8 z 10^-11 m and the electron makes 6.6 x 10^15 r/s, find;
a) the acceleration of the electron
b) the magnitude of the gravitational force of attraction between the electron and the nucleus
c) the centripetal force acting on the electron
d) the magnitude of each force contributing to the centripetal acceleration (name each force)

2. Relevant equations
Fc= ma= mv^2/r=4pi^2Rf^2
Fg=Gm1m2/r^2

3. The attempt at a solution
So I got the acceleration by using this equation: ac=4pi^2Rf^2= 9.97 x 10^22 m/s/s, and I know that the two forces contributing to the Fc are Fg and an electrical force of attraction. I do not know how to get the gravitational force of attraction without any masses. I'm at a loss. I also calculated the speed, but I do not see how I can use that to get the Fg and the Fc. Please help!

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#### rock.freak667

Homework Helper
Well you have Hydrogen which is just one proton and one electron. So you can look up the masses for these two and use it.

#### AudenCalbray

Well you have Hydrogen which is just one proton and one electron. So you can look up the masses for these two and use it.
I'm pretty sure I'm only supposed to use information provided from the question though..

#### rock.freak667

Homework Helper
I'm pretty sure I'm only supposed to use information provided from the question though..
They are standard values but in that case, then you can't find the gravitational force nor the centripetal force as they both contain a mass term.

#### AudenCalbray

Oh, alright, thank you!

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