Starting from rest at the ground floor, an elevator takes 19.0 seconds for a vertical trip of 70.0 meters. It begins its journey with 4.50 seconds of constant acceleration, then moves for 9.00 seconds at constant velocity, and finally, moves for 5.50 seconds of constant negative acceleration that brings the elevator to a stop.
(a) What is the maximum velocity of the elevator?
(b) What is the elevator's initial acceleration?
(c) What is its final acceleration?