Knowing that at the time of the release the balloon was 73.8 m above the ground, determine the time, τ, it takes the bag to reach the ground from the moment of its release.
Using the kinematics equation for displacement of an object under constant acceleration, d = v0t + 1/2 at^2 (where d is distance, v0 initial velocity, a acceleration, t time), we can solve for t.
This equation looks like: t = √(2d/a)
(v0t drops out since it is 0 at moment of release)
Assuming Earth gravity acceleration is 9.80 m/s^2, t = √((2(73.8)/9.80) = 3.88 s