Calculating Electric Force between Charged Balloon and Denim

[freeofwork]

Question:

A balloon rubbed aginst denim gains a charge of -8microC. What is the electric force between the balloon and the denim when the two are separated by a distance of 5.0 cm? (Assume that the charges are located at a point.)

Equations used:
F electric = K q1 X q 2 / r^2


Steps Tried:
How can I solve this is I only have one charge?

 

[SammyS]

Question:

A balloon rubbed aginst denim gains a charge of -8microC. What is the electric force between the balloon and the denim when the two are separated by a distance of 5.0 cm? (Assume that the charges are located at a point.)

Equations used:
F electric = K q1 X q 2 / r^2


Steps Tried:
How can I solve this is I only have one charge?

From where did the balloon pick up its charge ?

 

[freeofwork]

From where did the balloon pick up its charge ?

The denim.

 

[SammyS]

The denim.

So, what do you suppose the charge on the denim is after giving up -8 μC of charge ?

 

[freeofwork]

Is the balloon and denim at first neutral? Then I guess the balloon would have a -8microC and the denim a +8microC. If this is correct, then I know how to solve this problem.

Thank you for making my brain actively think!