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一、假设法例1某铜球的体积为8 cm~3,质量是26.7 g,问此铜球是空心的还是实心的?分析求出同体积的实心铜球的质量m宴,再跟题中已知的铜球质量m_球相比较,若m_实=m_球,则球是实心的;m_实>m_球,则球是空心的.解假设铜球是实心的,则铜球的质量m_实=ρ_铜V_球=8.9 g/cm~3×8 cm~3=71.2 g.因为m_实>m_球,所以铜球是空心的.二、列方程组法例2有一件铜、金两种金属做成的工艺品,体积是0.9 dm~3,质量是10 kg,求这件工艺品中铜、金的质量各是多少?分析工艺品的质量是铜、金的质量之和,工艺品的体积是铜、金的体积之和.
Suppose that the volume of a copper ball in Law 1 is 8 cm ~ 3 and the mass is 26.7 g. Ask whether this copper ball is hollow or solid. To analyze the quality of a solid copper ball of the same volume, Known copper ball mass m_ ball compared to, if m_ real = m_ ball, the ball is solid; m_ real> m_ ball, the ball is hollow. Solution Suppose the ball is solid, then The mass of copper ball m_ real = ρ_ copper V_ball = 8.9 g / cm ~ 3 × 8 cm ~ 3 = 71.2 g. Because m_ real> m_ ball, so the copper ball is hollow. Group Law 2 has a copper and gold made of two handicrafts, the volume is 0.9 dm ~ 3, the quality is 10 kg, find the handicrafts of copper, gold, the quality of each is how much? Crafts quality is copper, gold The sum of the quality of crafts is the volume of copper, gold and the sum of the volume.