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第94页

信息发布者：

$ ρ_醋=\frac {h_1}{h_2}ρ_水$

$ 解：(1)V_水=\frac {m_水}{ρ_水}=\frac { 200\ \text {g}}{1\ \text {g/cm}^3}=200\ \text {cm}^3$

$ V_石=V-V_水=300\ \text {cm}^3-200\ \text {cm}^3=100\ \text {cm}^3$

$ (2)ρ=\frac {m_石 }{V_石}=\frac { 25×10\ \text {g}}{ 100\ \text {cm}^3}=2.5\ \text {g/cm}^3$

$ 解：ρ1=\frac {m_{1} }{V_{1}}=\frac {3\ \text {g}}{1×1×1\ \text {cm}^3}=3\ \text {g/cm}^3$

$ ρ2=\frac {m_{2} }{V_{2}}=\frac { 24\ \text {g}}{2×2×2\ \text {cm}^3}=3\ \text {g/cm}^3$

$ ρ3=\frac {m_{3} }{V_{3}}=\frac {54\ \text {g}}{3×3×3\ \text {cm}^3}=2\ \text {g/cm}^3$

$ ρ_{3}<ρ_{2}=ρ_{1}，所以第三个是空心的$

$ V_实=\frac {m_3}{ρ_2}=\frac {54\ \text {g}}{3\ \text {g/cm}^3}=18\ \text {cm}^3$

$ V_空=V_{3}-V_实=3×3×3\ \text {cm}^3-18\ \text {cm}^3=9\ \text {cm}^3$