The height of a helicopter above the ground is given by h = 2.75t3, where h is in meters and t is in seconds. At t = 2.50 s, the helicopter releases a small mailbag. How long after its release does the mailbag reach the ground? the answer is 11.3 but I can never find out how to get that number, how to I do this?

Air inially occupying a volume of 1 m2 at 100 kpa, 27 c undergoes three internally reversible processes in series. process 1-2 compression to 500 kpa during which pv constant process 2-3 adiabatic expanslon to 100 kpa process 3-1: constant-pressure expansion to 100 kpa (a) calculate the change of entropy for each of the three processes. (b) calculate the heat and work involved in each process. (c) is this cycle a power cycle or refrigeration cycle?