looks fine to me
A charge of +q is located at the origin, while an identical charge is located on the x axis at x = 0.51 m. A third charge of +5q is located on the x axis at such a place that the net electrostatic force on the charge at the origin doubles, its direction remaining unchanged. Where should the third charge be located?
I worked this problem out as follows. Please point out if I go wrong.
F2=(kqq/.51^2)+(5kqq/x^2) which is equal to 2F1
Can somemone confirm this? I only have one more try on my homework.