14) A shell is fired from a gun, whose barrel is inclined at an angle to the horizontal. During the flight, the shell explodes into fragments. The center of mass of the different fragments will follow (A) a horizontal straight line, (B) a vertical straight line, (C) a parabola, or (D) an unpredictable path.
15) The rate of change of momentum of the raindrop can be represented by F = ma + uΔm/Δt. In this expression, what does u represent? (A) The velocity of the extra mass added to the raindrop, (B) The velocity of the raindrop, (C) The velocity of the loss in mass of the raindrop, or (D) The rate of change of velocity for the combined system.