Imagine a parallel universe in which the electric force has the same properties as in our universe but there is no gravity. In this parallel universe, the sun carries charge Q, the earth carries charge −Q, and the electric attraction between them keeps the earth in orbit. The earth in the parallel universe has the same mass, the same orbital radius, and the same orbital period as in our universe.

Question

Calculate the value of Q. (Consult Appendix F as needed.)
Express your answer using two significant figures.

Answer 1

Not having appendix F I'll ty to talk you through it. First you need the gravitational force between Earth and the sun. Get this from F = GmM/r^2. Next just use Coulomb's Law
F (the one you just found) = kQ^2/r^2.
In fact you can save a step and ignore the distance between them with
Q = sqrt(GMm/k).
G = 6.67e-11, k = 9e9, m = 5.98e24 but I don't know the mas of the sun offhand