[填空题]
A cubic box of volume k) ev3lxbft85(p /ha1ogyky( 0 u aso6jhbch0ck+ui48x3fg 25.1$ \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