12题∵P=ρgh ∴ρ=P/gh=2352Pa/（0.7m*10N/kg)=0.336*10^3kg/m^3。
11.P=ρgh=1*10^3kg/m^3*10N/kg*0.2m=2*10^3Pa12.∵P=ρgh∴ρ=P/gh=2352Pa/（0.7m*10N/kg)=0.336*10^3kg/m^3
