# Electric force between objects that are in brief contact

1. Mar 25, 2013

### Jabababa

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

Two small charged objects of the same mass and volume are brought into brief contact with each other. If the initial charges on the two objects are -3.00 x10^-6 and -1.50 x10^-6, what is the electric force between the objects when they are seperated to a distance of 0.500m after contact?

The answer is 1.82 x10^1 N

2. Relevant equations

F=KQ1Q2/r^2

3. The attempt at a solution

I thought it is just plug in the numbers but i get a different answer. So is there anything that goes on when they are in contact?

F= (9.0x10^9)(-3.00x10^-6)(-1.50x10^-6)/(0.500)^2
=0.162N

2. Mar 25, 2013

### ap123

The important thing here is that they are brought into contact first.
What changes does that cause?

3. Mar 25, 2013

### Jabababa

im not really sure...

umm their initial distance? Or it will have to be something to do with their charge (transfer of electro maybe)?

4. Mar 25, 2013

### tia89

I think the objects you have are conductors?? What happens in this case?? And anyway are you sure the result is not 1.82x10^(-1)?? (you put 10^1)...

5. Mar 25, 2013

### ap123

I think you have to assume they're conductors, since it gives the right answer :)

Yes - this is the answer I got.

Jabababa - When you put two unequally charged conductors in contact, what happens to the charges on them?

6. Mar 25, 2013

### tia89

Just as I thought