(a)
v₀ = initial velocity of the roller coaster = 0 m/s
v = final velocity of the roller coaster = 33.5 m/s
t = time of travel = 4 seconds
a = magnitude of average acceleration
magnitude of average acceleration is given as
a = (v - v₀)/t
a = (33.5 - 0)/4
a = 8.375 m/s²
b)
m = mass of the rider = 45 kg
a = magnitude of acceleration of the rider = 8.375 m/s²
F = average net force on the rider
average net force on the rider is given as
F = ma
F = 45 x 8.375
F = 376.875 N