A box is dropped from a plane from a height of 31,360 m. How long will it take to hit the ground

With work?

Known:
H =31360 m
a = g = 9.81 m/s^2

hf= final height = 31360m
hi = initial height = 0
v= initial velocity = 0 (object was at rest)

hf= hi + vt + 1/2(gt^2)
Solve for t:
t= sqrt(2hf/g)
So,
t=sqrt((2*31360m)/9.81 m/s^2))

t= 79.959 seconds
apx 80 seconds

How many LBS. is the box.