# Homework Help: Heeeeeelp me

1. Mar 21, 2009

### afm-91

plzz,,,heeeeeelp me

In a simple model of the hydrogen atom, the electron revolves in a circular orbit around the proton with a speed of 2.2*10^6.

Determine the radius of the electron's orbit???

2. Mar 21, 2009

### danago

Re: plzz,,,heeeeeelp me

Have you made an attempt? What are your thoughts on the problem?

3. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

I do not understand the problem

Last edited: Mar 21, 2009
4. Mar 21, 2009

### danago

Re: plzz,,,heeeeeelp me

What forces are present in this simple model, and how can you relate them to the circular orbit? (i.e. what is providing the centripetal force?)

5. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

???

6. Mar 21, 2009

### The Liberator

Last edited by a moderator: Apr 24, 2017
7. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

V^2/a ???

but l dont have (a) in my problem !!!!

8. Mar 21, 2009

### danago

Re: plzz,,,heeeeeelp me

Where did v^2/a come from? Did you mean $$a_c=\frac{v^2}{r}$$?

9. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

yes!!

10. Mar 21, 2009

### danago

Re: plzz,,,heeeeeelp me

Ok. Since there is an acceleration, there must be a force, right?

What could possibly be providing this force? In which direction will it act?

11. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

centripetal force

the direction to the center

12. Mar 21, 2009

### danago

Re: plzz,,,heeeeeelp me

Yea, there is a centripetal force, but what causes it to exist? For example, a car can travel in a circular path because of the friction between the tires and road surface.

13. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

i dont know

14. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

because of the acc. ??

15. Mar 21, 2009

### Mentallic

Re: plzz,,,heeeeeelp me

What does the nucleus of the atom consist of? How are these sub-atomic particles in the nucleus different to the electron orbiting the nucleus?

16. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

What does the nucleus of the atom consist of? n+ p

How are these sub-atomic particles in the nucleus different to the electron orbiting the nucleus? ........

17. Mar 21, 2009

### Mentallic

Re: plzz,,,heeeeeelp me

Yes, there are neutrons and protons in the nucleus. Now, what is the electric charge of each particle? positive/neutral/negative?

18. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

p >>>>positive

n>>>>>neutral

19. Mar 21, 2009

### Mentallic

Re: plzz,,,heeeeeelp me

Yep, and the electron is negative.
Ok, so how do electric charges interact? i.e. a positive and a negative electric charge will do what to each other?

20. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

Attract each other

21. Mar 21, 2009

### Mentallic

Re: plzz,,,heeeeeelp me

Correct. Now can you see where the centripetal force is coming from in order to keep the electron in orbit?

22. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

????????????????/
protons

23. Mar 21, 2009

### afm-91

Re: plzz,,,heeeeeelp me

any body can help me ????????

24. Mar 21, 2009

### ImAnEngineer

Re: plzz,,,heeeeeelp me

Hint: Coulombs law

25. Mar 21, 2009

### Mentallic

Re: plzz,,,heeeeeelp me

Err... The answer you've given me is like answering "what keeps the moon orbiting Earth" with "Earth".
But since you've answered the question in parts, yet have been unsuccessful in laying it out into a sentence, then I'll throw it onto a platter for you: "The electrons orbit the nucleus of the atom because of the electrical attraction of the proton and electron due to their opposite charges"

So now we know what is providing the centripetal force (The force that keeps the electron from flying off in a straight line as defined by newton's first law).

Again, using the equation $$a_c=\frac{v^2}{r}$$
where ac= centripetal acceleration
v=velocity