The discovery which Carnot made was that THE DIFFERENCE IN THE TEMPERATURES BETWEEN THE HOT AND THE COLD RESERVOIRS DETERMINE HOW WELL A HEAT ENGINE WOULD WORK. Sadi Carnot was a French engineer, He proposed a theoretical thermodynamic cycle in 1824. In his cycle, Said hold that the efficiency of a heat engine depends on the temperature difference between its hot reservoir and cold reservoir.
The velocity of the package relative to the ground = the velocity of the package relative to the helicopter + the velocity of the helicopter relative to the ground
v = 0 m/s + 2.5 m/s
v = 2.5 m/s
At the moment it is released, the package is rising at 2.5 m/s.