Need help on how to find distance between electron and proton

[ken19]

1. According to the "Solar model" of a single ionized Helium atom has one electron revolving in a circular orbit around a stationary nucleus made of two protons and two newtrons. The diameter of this atom is .95*10^-10m. Use Coulomb's law and calculate the speed of the electron (m/s) in its orbit.

2. Homework Equations
Fe=K*q1*q2/d2 where k=8.99*10^9 Nm^2/s^2.
v=d/t

3. The Attempt at a Solution .
How do I go about solving this question when either of distance or time is given? Any help is appreciated.

 

[jackqpublic]

consider the protons as in the center of the atom.
the definition of atomic radius is the distance from the center of the atom to its farther electron.
so use the definition of centripetal force and you will get the velocity of the electron.
[;F=\frac{mv^2}{R};]
and [;F=\frac{K.Q_1.Q_2}{R^2};]