A coal car with an empty mass of $25 \mathrm{Mg}$ is moving freely with a speed of $1.2 \mathrm{m} / \mathrm{s}$ under a hopper which opens and releases coal into the moving car at the constant rate of $4 \mathrm{Mg}$ per second. Determine the distance $x$ moved by the car during the time that $32 \mathrm{Mg}$ of coal are deposited in the car. Neglect any frictional resistance to rolling along the horizontal track.