Final answer:
Without additional data, we cannot calculate the final velocity of the boxcar after the water has leaked out. We need to consider the mass of the boxcar, the water, and the initial velocity to use the conservation of momentum to find the answer.
Step-by-step explanation:
To determine the final velocity of the boxcar after all the water has leaked out, we need to apply the conservation of momentum. The question provided does not include all of the necessary data to solve the problem; however, based on the principle of conservation of momentum, if there is no external force acting on the system (boxcar plus water), and if the water leaks out in such a way that it doesn't impart an additional force on the boxcar, the velocity of the boxcar would not change due to the water leakage alone.
In a provided example, a freight car has a mass and initial velocity given, and it is loaded with additional mass from a hopper. Assuming the system is closed and there are no external forces, the conservation of momentum would dictate the final velocity of the freight car. For the question at hand, without specific numbers for the initial mass of the boxcar, the mass of the leaked water, and the initial velocity of the boxcar, we cannot provide a definitive answer from choices a) to d).