(1)木块的边长:
a=
=0.1m,
3
1×10?3m3
木块排开水的体积:
V排=a2(a-h1)=(0.1m)2×(0.1m-0.05m)=5×10-4m3,
木块受到的浮力:
F浮=ρ水gV排=1.0×103kg/m3×10N/kg×5×10-4m3=5N;
(2)水面上升高度:
h2=
=V排 S
=1.25×10-2m,5×10?4m3
0.04m2
增加的压强:
p=ρ水gh2=1.0×103kg/m3×10N/kg×1.25×10-2m=125Pa;
(3)露出液面高度为h3=4cm,木块排开液体的体积:
V排′=a2(a-h3)=(0.1m)2×(0.1m-0.04m)=6×10-4m3,
∵木块漂浮:
F浮′=G,
即:ρ液gV排′=G,
ρ液=
=G gV排′
≈0.83×103kg/m3.5N 10N/kg×6×10?4m3
答:(1)木块受到的浮力为5N;
(2)投入木块后,容器底增加的压强为125Pa;
(3)这种液体的密度0.83×103kg/m3.