a) 12.5 m
Explanation:
During the acceleration phase, the distance travelled by the elevator is given by:
where
v = 5 m/s is the final speed of the elevator
u = 0 is the initial speed
a = 1.0 m/s^2 is the acceleration
d is the distance travelled
Using the equation, we can find d:
b) 45 s
Explanation:
The distance covered during the acceleration phase is 12.5 m. The distance covered during the de-celeration phase, at the end of the trip, is exactly the same (because the values of u, v and a are the same). The total distance is 200 m, so the distance covered at a constant speed of 5 m/s is
This distance is covered at a speed of v=5 m/s, so the time taken is
The time the elevator takes to cover the 12.5 m in the acceleration phase is
and the same for the deceleration phase; therefore, the total time for the trip is