What is the new separation between the charges?

[kdrobey]

Homework Statement

Two positive point charges are held in place, 0.86 m apart. They are then moved so that their electric potential energy doubles. What is the new separation between the charges?

Homework Equations

kq/r

The Attempt at a Solution

had PEb=KQaQb/d=2EPEa, then did KQaQb/d=2(KQaQb/.86. but cannot figure out how to solve it further

 

[Doc Al]

... then did KQaQb/d=2(KQaQb/.86.

This is good. Simply and solve for d. Start by canceling everything that can be canceled from both sides of the equation.

 

[kdrobey]

both sides of the equation had KQaQb, i canceled the part out on both sides, leaving, 1/d=2(1/.86). then 1=2.32d. d=.43?

 

[Doc Al]

Looks good to me.

 

[kdrobey]

awesome, thanks