∵1MPa=1000kPa=1000kN/m²=1000kN/10000cm^2=0.1kN/cm^2∴1kN/cm^2=10MPa受力面积S=7cm×7cm=49cm^2压力F=18kN压强P=F/S=18/49≈0.367kN/cm^2=0.367×10=3.67MPa
