An airplane pilot experiences weightlessness as she passes over the top of a loop-the-loop maneuver. if her speed is 200 m/s at the time, find the radius of the loop.

Centripetal acceleration is given by:
g=v^2/r
where:
v=velocity
r=rate
But
V=200 m/s, g=9.8 m/s^2
plugging the values in the formula we obtain:
9.8=200^2/r
r=200^2/9.8
r=4081.63 m