Two identical stones, A and B, are released simultaneously from the same point: stone A is projected vertically upward with a speed of 15\,m/s, while stone B is allowed to fall freely from rest. Air resistance is negligible.
(i) Identify the magnitude and direction of the net force acting on each stone during the first 2\,s after release.
(ii) Compare the accelerations of A and B during the following intervals: (a) while stone A is ascending, (b) while stone A is descending, and (c) at the highest point of stone A.
(iii) Using Newton’s second law, justify whether either stone is ever in a state of weightlessness during its motion.