# Rearrange equation

1. Apr 17, 2010

### missyfit

1. The problem statement, all variables and given/known data

F = A [Q][1][Q][2] / [r][2]

Rearrange make A subject

any one have any ideas?

2. Relevant equations

3. The attempt at a solution

2. Apr 18, 2010

### tiny-tim

Welcome to PF!

Hi missyfit! Welcome to PF!

(try using the X2 and X2 tags just above the Reply box )

Do you mean F = A Q1Q2 / r2 ?

Just move the Qs and the r to the other side…

what do you get?

3. Apr 18, 2010

### missyfit

F = A Q1Q2 / r2 ?
yes this is what was meant thanks

by moving the Qs and r to other side is A the subject if it is left on the right?

4. Apr 18, 2010

### Redbelly98

Staff Emeritus
Yes.

5. Apr 18, 2010

### tiny-tim

Or you can always swap the sides round, if it makes you happier.

6. Apr 18, 2010

### missyfit

Thanks for both you inputs can you give an example of how you may work this out. do i need to do anything with the sqare root?

missyfit

7. Apr 18, 2010

### tiny-tim

No, you show us what you think, and we'll comment.

8. Apr 18, 2010

### missyfit

first i thought that swaping side over then wasnt sure what i should do with square root

F = A Q1Q 2 / r2
A Q1Q2 / r2 = F
A Q1Q2 / r2 x Q1Q2 / r2 = F Q1Q2 / r2 x Q1Q2 / r2
A = F Q1Q2 / r2

this all seems abit bulky.

9. Apr 19, 2010

### tiny-tim

Hi missyfit!

(just got up :zzz: …)
uhh? whatever are you doing?

start again.

10. Apr 19, 2010

### missyfit

I guess i made a mess of this just learning equations and already finding it stressful. Dont worry thanks for help any way was following system we have been given to do equation clearly not very effective. :uhh:

11. Apr 20, 2010

### tiny-tim

Hi missyfit!

(just got up :zzz: …)

Start by multiplying both sides of the original equation by r2

what do you get?