[填空题]
A cubic box of volumqqhp hsu;x6l m9rdjta,cih)07 *a 39m cd :.hue7 2uc9zxgml8c 5.1$ \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