# Centripetal Acceleration ?

## Homework Statement

The mass of an electron is 9 x 10-31 kg. The mass of a proton is 1.7 x 10-27 kg. The proton and electron are about 1.0 x 10-10 m apart in a hydrogen atom. What force of gravitation exists between the proton and the electron of a hydrogen atom? What is the centripetal acceleration of the electron?

## Homework Equations

Fg = G*m1*m2/d^2
* Fg is the magnitude of the gravitational force between the two point masses,
* G is the gravitational constant,
* m1 is the mass of the first point mass,
* m2 is the mass of the second point mass,
* r is the distance between the two point masses.

ar = v2 / r

ar is centripetal acceleration
v is velocity in meters per second,
r is the radius of the circle in meters

## The Attempt at a Solution

I plugged in the infomation to find the gravitational force and got 1.02051 x 10^-47
but it doesn't give us the nessicary information to find the centripetal acceleration... I don't think.. can anyone help me with this?

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Doc Al
Mentor
What provides the centripetal force?

It rotating around the hydrogen atom I think...

Doc Al
Mentor
It rotating around the hydrogen atom I think...
The electron "orbits" the proton. Again, what provides the centripetal force?

I suppose im not sure what you mean.. or what provides it... that is all the question said...

Doc Al
Mentor
What force holds the atom together? (It's not gravity.)

The electrical charge of the atom?

Doc Al
Mentor
The electrical charge of the atom?
Right. The electric force provides the centripetal force. How much is the electrical force? (Hint: Coulomb's law) Once you have the centripetal force, use Newton's 2nd law to find the acceleration.

5.508 x 10^-27 N is what i got when i plugged it in...
and for the acceleration i got 6120 meter/second^2

Last edited:
Doc Al
Mentor
5.508 x 10^-27 N is what i got when i plugged it in...
and for the acceleration i got 6120 meter/second^2