# Electron orbiting proton-orbital radius?

#### awertag

Electron orbiting proton--orbital radius??

1. Homework Statement

In the Bohr model, the electron is imagined to move in a circular orbit about a stationary proton. If the speed of the electron were 8.9e5 m/s, what would be the corresponding orbital radius?

2. Homework Equations

3. The Attempt at a Solution
Fe=ma
a=Fe/m
(v^2)/r=(kqq/r)/m
v^2rm=kqq
(8.9e5)(r)(9.11e-31)=(9e9)(1.6e-19)(-1.6e-19)
r=-2.842e-4m

I hope you can help!!

--aweg

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#### SammyS

Staff Emeritus
Homework Helper
Gold Member
Re: Electron orbiting proton--orbital radius??

1. Homework Statement

In the Bohr model, the electron is imagined to move in a circular orbit about a stationary proton. If the speed of the electron were 8.9e5 m/s, what would be the corresponding orbital radius?

2. Homework Equations

3. The Attempt at a Solution
Fe=ma
a=Fe/m
(v^2)/r=(kqq/r2)/m
v^2rm=kqq
(8.9e5)2 (r)(9.11e-31)=(9e9)(1.6e-19)(-1.6e-19)
r=-2.842e-4m

I hope you can help!!

--aweg
Some corrections are in red above.

Also, r should not be negative. There's one more error above which made r come out to be negative.

I assume you mean 10‒4 when you write e‒4, etc.

#### awertag

Re: Electron orbiting proton--orbital radius??

is the other error that i included the sign for electron charge?

#### awertag

Re: Electron orbiting proton--orbital radius??

ok well now i got r=3.193e-10 meters which is positive, so that's good...but i'm pretty sure it's not right, either

#### awertag

Re: Electron orbiting proton--orbital radius??

and yes e5 is x10^5

#### awertag

Re: Electron orbiting proton--orbital radius??

oh just kidding that was correct!! :D thank you so much!!

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