ANSWER:
4 sec
Explanation:
Given:
Mass (m) = 50 kg
Speed (v) = 2.5 m/s
Work (W) = 4900 J
Speed is constant then a = 0
Net applying force = 0 N
We make the vertical force balance:

Now we calculate the distance:

Now, we calculate the time using the speed formula:

The time of the elevator trip is 4 seconds