Finding charge for moon-Earth Coulomb force equal to gravity

[chrish]

hi, thanks for helping me.

heres the question

Suppose the moon had a net negative charge equal to -q and Earth had a net positive charge equal to +10q. What value of q would yield the same magnitude force that you now attribute to gravity?

(answer in coulombs) I have it on a thing called webassign, and you can only have 15 tries... i used 14. here are my wrong attempts:
1.6e-19
1.6e-18
-1.6e-18
-1.6e-20
1.6e-20
1.6e18
8.99e10
-8.99e10
.1
-.1
8.99e9
-8.99e9
-8.99e8
-10

 

[Pengwuino]

https://www.physicsforums.com/showthread.php?t=94379

We will not do your homework for you, we will only help. Did you read the guidelines?

 

[andrevdh]

The gravitational attraction must equal the electrostatic attraction
$$\frac{Gm_em_m}{r^2} \ = \ \frac{kq_1q_2}{r^2}$$