Bohr's Atom Model Questions

[Taher_Selim]

Hello Guys,
I was reviewing Bohr's Atom model. I got the following question that couldn't find answer by me:

All sources that I have reviewed equates centripetal force of the electrons with attractive force. they are using coulomb's law to describe the attractive force. They used the following formula:
F = (e^2)*K/r^2
However an attractive force due to Coulomb's law is:
F = - (e^2)*K/r^2
I mean there is negative sign that is missed in the first formula.
Do you have any explaination for discarding this sign?

 

[kabiru]

This means the total energy is negative and inversly proportinal to it's radius,the energy is pulling out the orbiting electron away from the inner shell(proton)for infinite value of 'r'and the energy said to be zero.

 

[Taher_Selim]

Hello Kabiru,
Can you please give more clarification.

 

[zorro]

No! No negative energy!
The sign is related to the sense of the force. Teh sense is a convention.
If you consider that positive force is towards the centre, then the resulting sign is positive, and otherwise it is negative.
Regards

Z