(2014? Jining) Hang a metal block at the lower end of a spring dynamometer and immerse it in water and alcohol. When the metal block is stationary, the reading of the spring dynamometer is as shown in

(1) An object immersed in a liquid is affected by buoyancy, gravity, and pull. The relationship is G=F float F pull.

Immersed in water: G=F float 1 F Pull 1, immersed in alcohol: G = F float 2 F pull 2,

That is, F float 1 F pull 1 = F float 2 F pull 2,

And by Aki Meade's principle F float = ρ liquid gV discharge,

ρ water gV discharge F pull 1 = ρ alcohol gV discharge F pull 2,

1.0×103kg/m3×10N/kg ×V row 2N=0.8×103kg/m3×10N/kg×V row 2.2N,

V row=1×10-4m3,

The object is completely immersed, so V object =V row=1×10-3m3, so option C is wrong;

(2) The buoyancy force F floated in the water =ρ liquid gV row=1.0×103kg/m3×10N/kg×1× 10-4m=1N, so option A is wrong;

(3) When immersed in water, the gravity G=F floats 1 2N=1N 2N=3N,

The mass m=Gg =3N10N/kg=0.3kg; therefore B is wrong;

(4) The density of the object is ρ=mV=0.3kg1×10-4m3=3×103kg/m3, so option D is correct.

So choose D.