As a helicopter carrying a crate takes off, its vertical position (as well as the crate's) is given as: y(t) = At^3 where A is a constant and t is time with t = 0 corresponding to when it leaves the ground. When the helicopter reaches a height of 15.0 m a crate falls from the underside of the aircraft. From the time the crate leaves the helicopter to the time it hits the ground, 3.5 seconds pass. Calculate A. Which Physics principle laws or definitions did you use?