# Finding the distance of 2 charges

## Homework Statement

On attachment called Part B

## Homework Equations

To get part A, I used a formula that I derived to be:

square root [(2kq^2)/rm)] = v

where
q =2.6 *10^-6 C
k = 8.99*10^9 (Nm^2)/C^2
r = 1.27m
m = .0028 kg

## The Attempt at a Solution

Now for part B it says to calculate the distance r when it is half of v, so I thought maybe I could rearrange the equation above to

(2kq^2)/((v^2)*m) = r

so it would look like...

[2 * 8.99^9 * (2.6*10^-6)^2]/[((5.84/2)^2)*.0028] = r

I used dimensional analysis and it comes out to be

[(Nm^2/C^2)C^2]/[(kgm^2)/(s^2)]

then I cancel what I can to get

(Ns^2)/kg which in turn, becomes

1ms^2/s^2 which at the end turns out to be left with only meters...

So it seems like I'm right but obviously im not...

OK in the attachment are the answers I submit after doing so many bizaarrreee calculations... ANy help would be appreciated... I think the reason I'm not getting hte correct answer is becuase the question states "at infinity" and I have no Idea what that means...

#### Attachments

• Part B.JPG
46.2 KB · Views: 361
Last edited: