Answer:
39.0 s
Step-by-step explanation:
First find the time and distance the elevator takes to accelerate or decelerate.
Given:
u = 0 m/s
v = 4.00 m/s
a = 3.00 m/s²
Find: t
v = at + u
4.00 = (3.00) t + 0
t = 1.333 s
Find: s
v² = v₀² + 2as
(4.00)² = (0)² + 2(3.00)s
s = 2.667 m
Next, find the time the elevator spends at constant speed.
Given:
s = 35 × 4.30 m − 2 × 2.667 m = 145.167 m
u = 4.00 m/s
a = 0 m/s²
Find: t
s = u t + ½ a t²
145.167 = (4.00) t + ½ (0) t²
t = 36.3 s
So the total time is:
2 (1.333 s) + 36.3 s = 39.0 s