Here it is given that initial speed of the package will be same as speed of the helicopter
displacement of the package as it is dropped on ground
acceleration is due to gravity
now by kinematics
by solving above equation we have
so it will take 5.2 s to reach the ground
The correct answer is:
Work is negative, the environment did work on the object, and the energy of the system decreases.
In fact, the work-energy theorem states that the work done by the system is equal to its variation of kinetic energy:
In this problem, the variation of kinetic energy is negative (because the final velocity is less than the initial velocity), so the work is negative, and this means that the environment did work on the object, and its energy decreased.