(1)物体浸没在液体中时.W额外/W总1=1-η1,G动h/F1nh=G动/(3X60)=1-40%,G动=108N
物体离开液体后F2=（G动+GA）/3,GA=3F2-G动=3X80-108=132N
η2=W有用2/W总2=GAh/nF2h=132/(3x80)=55%
(2)物体浸没在液体中时.W有用1/W总1=η1,(GA-F浮)h=η1F1nh=40%x60x3h=72h
F浮=GA-72=132-72=60N
3/2ρ水gVA=60,VA=40/（ρ水g）
GA=ρAgVA,132=ρAgx40/（ρ水g）,ρA=3.3ρ水=3.3x103kg/m3