Help me solve questions 8, 9, 10, 12, 13, 14, 16, 17 and 18

According to newtons universal law of gravitation, which would change the parh of the ball so it traces out widest curved path possible?

Along the line connecting the two charges, at what distance from the charge q1 is the total electric field from the two charges zero? express your answer in terms of some or all of the variables s, q1, q2 and k =14ï€ïµ0. if your answer is difficult to enter, consider simplifying it, as it can be made relatively simple with some work.

(**i would really appreciate if this was answered soon** ) which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?