解：?$(2)F_{浮}=G-F=2.5\ \text {N}- 1.5\ \text {N}=1\ \text {N}$?
?$(3)\frac {ρ}{ρ_水}=\frac {ρgV}{ρ_水gV}=\frac {G}{F_浮}=2.5 ，$?得?$ρ=2.5 ρ_水=2.5 ×10^{3}\ \text {kg/m}^3$?
?$(4)p=ρgh=2.5×10^{3}\ \text {kg/m}^3×10\ \text {N/kg}×2\ \text {m}=5×10^{4}\ \text {Pa}$?
