## BaoZhu one year ago One way to write Coulomb's law is F=(k lQql)/(r^2) where F is the magnitude of the electric force, k is a constant, Q and q are the two electrical charges and r is the distance between them. Solve Coulomb's law for r.

1. douglaswinslowcooper

Multiply both sides by r^2, to get it on the left. Divide both by F, to get it on the right. r^2 = etc. r = sqrt(etc.) you should finish it.

2. BaoZhu

i did it, and it gave me r=+,-(sqrt(k(Qq))/(sqrt(F)), however, the system still reads it as incorrect, is there i'm missing with the absolute value of “Qq”？

3. douglaswinslowcooper

r cannot be negative as it is a distance. Did you use |Qq| or (Qq)? Former is needed.

4. BaoZhu

i can not use capital Q, because wileyplus(the software) do not allow me to.

5. BaoZhu

6. douglaswinslowcooper

You have the right formula for the answer.

7. BaoZhu

so, it's the system itself that is not accepting the answer?and not that my answer is incorrect?

8. RaphaelFilgueiras

you forget the modulus inside sqrt

9. BaoZhu

so there it should be absolute value of q1q2?

10. RaphaelFilgueiras

yes , imagine ,if the value of product were negative will give you an complex radius

11. BaoZhu

12. BaoZhu

will that be the answer? sorry about all the questions, i don't want to submit the answer before it is right since i only have 1 more attempt left.