Here is the question I am stuck on:

A plane is to perform the top part of a vertical loop at a speed of 2.50x10^2 m/s. What radius arc must the plane make in order to give the passengers the sensation of weightlessness at the top of the loop?

If the plane makes an arc with a radius of 8.00x10^3m what is the reaction force from the plane onto a 75.0kg passenger when the plane is at the very top of the loop?

For the first question, would weightlessness be reached when mg=mv^2/r or when mg is greater than mv^2/r?

Any help is appreciated!