Afreight car moves along a frictionless level railroad track at constant speed. the freight car is open on the top. a large load of sand is suddenly dumped into the freight car. what happens to the speed of the freight car? a freight car moves along a frictionless level railroad track at constant speed. the freight car is open on the top. a large load of sand is suddenly dumped into the freight car. what happens to the speed of the freight car? the speed of the freight car remains the same. the speed of the freight car increases. the speed of the freight car decreases. it is impossible to determine whether the speed of the freight car increases or decreases from the information given.