Problems on the dynamics of changing mass systems often call for the more general form of Newton's second law Fnet = dp/dt. These problems usually involve situations where the mass of the system decreases, such as in rocket propulsion. In contrast, this experiment examines a system where the mass "increases" at a constant rate and the net force remains constant. This system provides a context that is different, and in some ways simpler, than the rocket propulsion systems typically introduced in introductory courses.