A pilot flies an airplane in a vertical circular loop at a constant speed õ = 160 m/s. If the pilot’s apparent weight at the top of the loop is one-third of his true weight when he is on the ground, find the radius R of the plane’s circular path.

Question

answer is 1960 m but i need help getting it

Answer 1

Apparent weight at the top of the loop is
M g - M V^2/R = (1/3) M g
Therefore
V^2/R = 2g/3

R = (3/2)V^2/g

I get twice what you say is the answer.