
Prakrati A. answered 04/19/21
Experienced primary and high school tutor for Maths and Science
At the bottom, the rider is feeling a force in the upward direction due to the centripetal acceleration due to moving in a circular way and also feeling a force in the downward direction due to gravity.
Centripetal acceleration is v2/r = (6 X 6)/8 = 9/2 m/s
Therefore net force on the 40 kg rider will be mg - ma in downward direction.
m(g - a) = 40(10-4.5) = 40 X 5.5 = 220 N