Physics question, average net force

a ride at an amusement park have magnets that shoot the ride from rest to 45m/s (about 100mi/h) in a time of 7.0s. the combined mass of the car and the riders is 5.5x10E3 kg. find the averag net force exerted on the car and the riders by the magnets.

Acceleration = (v/t), = 45/7, = 6.428m/sec^2.
Force = (ma), = 5500 x 6.428, = 35,354N.