[填空题]
A cubic box of volume +p4bj6n- c6bw1qeg7mo irw)toz0vgl x;ay7+wu-7qo x2nx/h5.1$ \times10^{ -2}m^3$ is filled with air at atmospheric pressure at 20 $^{\circ} $ C. The box is closed and heated to 180 $^{\circ} $ C. What is the net force on each side of the box? N