physics
posted by Sarah on .
A 57.0 kg child takes a ride on a Ferris wheel that rotates four times each minute and has a diameter of 23.0 m.
(a) What is the centripetal acceleration of the child?
(b) What force (magnitude and direction) does the seat exert on the child at the lowest point of the ride?
(c) What force does the seat exert on the child at the highest point of the ride?
(d) What force does the seat exert on the child when the child is halfway between the top and bottom?
I got the centripetal acceleration, it is 2.02 m/s^2. I just can't seem to figure out the rest of this problem.

a) acceleration= v^2/r=(23PI/15)^2 /(23/2)