# Two equal charges repel one another with a force of 4.0 x 10-4 N when they are 10 cm apart.?

Two equal charges repel one another with a force of 4.0 x 10-4 N when they are 10 cm apart. If they are moved until the separation is 20 cm, the repulsive force will be

### 4 Answers

- electron1Lv 75 months ago
The following equation is used to calculate the force.

F = k * q1 * q2 ÷ d^2

In this problem, the only thing that changes is the distances between the two charged objects. As you look at this equation, you can see that the force is inversely proportional to the square of this distance. Since the distance is doubled, the force is one fourth of the original force.

F = ¼ * 4 * 10^-4 = 1 * 10^-4 N

I hope this helps you to understand how to solve this type of problem.

- Andrew SmithLv 75 months ago
As F = kQq/ R^2

eliminate all that is constant and get

F is proportional to 1/r^2

ie F2/F1 = (R1/R2)^2 = (10/20)^2 = 1/4

and of course 1/4 of 4.0 * 10 ^ -4 = 1.0 * 10 ^ -4

I wouldn't even know how to make a guess....care to explain?