m酒=p酒V酒=0.8g/cm³*100cm³=80g=0.08kg
F=G=mg=(m杯+m酒)g=(0.12kg+0.08kg)*10N/kg=2N
S=20cm²=0.002m²
桌面受到的压强p=F/S=2N/0.002m²=2000pa