Loop velocity

1. Sep 30, 2010

PhysicStorm

An airplane flies in a loop (a circular path in a vertical plane) of radius 190 m. The pilot's head always points toward the center of the loop. The speed of the airplane is not constant. The airplane goes slowest at the top of the loop and fastest at the bottom.

(a) At the top of the loop, the pilot feels weightless. What is the speed of the airplane at this point?

(b) At the bottom of the loop, the speed of the airplane is 300 km/h. What is the apparent weight of the pilot at this point? His true weight is 700 N.

I have tried this problem multiple times and i used the formula of
accel = v^2/r
i know that accel is also equal to net force of the pilot divided by his mass so and that at the top of the loop it is equal to force of gravity down and force of normal force from seat

the masses do cancel out using
(9.8(m)+Fn)/m = v^2/190
i might be solving for normal force wrong can someone clear it up for me please?
w/o part a correct part b is always going to be incorrect. ty for your time and effort

2. Sep 30, 2010

betel

Why do you include the normal force coming from the chair? In normal flight this will just cancelthe gravitational force, but at the top, if the pilot is weightless there will be no force coming from the seat.