physics help please?

Question

The condition of apparent weightlessness for the passengers can be created for a brief instant when a plane flies over the top of a vertical circle. At a speed of 250 m/s, what is the radius of the vertical circle that the pilot must use?

thank you

Answer 1

Fc=W
ac m = mg or simply

ac= g since centripetal acceleration is related to tangential velocity V and radius R as
ac=V^2/R
we have
R= V^2/ac=V^2/g
R= (250)^2/9.81=6,370 m