Robots for Skyscaper Elevator Construction

(II) High-speed elevators function under two limitations: (1) the maximum magnitude of vertical acceleration that a typical human body can experience without discomfort is about 1.2 m / s^2, and (2) the typical maximum speed attainable is about 9.0 m / s . You board an elevator on a skyscraper's ground floor and are transported 180 m above the ground level in three steps: acceleration of magnitude 1.2 m / s^2 from rest to 9.0 m / s , followed by constant upward velocity of 9.0 m / s , then decel