How long will the object take to hit the grade?

Drop an object from 380m high.

How long will it take to hit the ground using this formula.

time will be in seconds, and velocity will be in m/s.

height= -4.9 t2+(initial velocity)t + initial height

I tried to solve it and i got 8.91 seconds. Am i right?

height= -4.9 t2+(initial velocity)t + initial height
height=0m , initial velocity=0m/s , initial height=380m
0= -4.9t^2+0+380
4.9t^2= 380
t^2= 380/4.9
t= √(380/4.9)
t= 8.8063 = 8.81[s] approx.

Use the following equation.
d = vi * t + ½ * a * t^2
In this problem, d is 380 meters, vi is 0 m/s, and a is 9.8 m/s^2

380 = ½ * 9.8 * t^2
t = √(380 ÷ 4.9) = 8.806305719 seconds
This is approximately 8.81 seconds.