There is an old elevator in Physics Building. One day Pan took the elevator from the first floor to third floor, which takes 5 seconds. The acceleration of the elevator in the first and last second of ascending had the same magnitude but opposite directions. During the rest of the time, the elevator ascended with a constant velocity. a. Suppose the magnitude of the acceleration is , calculate the displacement of the elevator in the first second and last second.

b. Calculate the constant velocity in terms of when elevator stopped accelerating.

c. Suppose the height of one floor is 5 meters. Calculate the value of and .

d. Draw a velocity vs. time graph for the elevator.