为了研究物质的某种特性，某同学选用了三种不同材料制成的长方体样品，他在实验中测量和经过计算的数据见下表。                                                                                                                                                                                                                                                                                                        

实验次数	样品	质量/g	体积/cm3	(g·cm-3)
1	铝块1	21.6	8.0	2.7
2	铝块2	43.2	16.0	2.7
3	松木1	4.0	8.0	0.5
4	松木2	16.0	32.0	0.5
5	铜块	71.2	8.0	8.9