小明在探究“弹簧的伸长量与拉力关系”时，利用如图1所示的实验装置进行实验，记录的数据如下表。                                                                                                                                                                                                                          

实验次数	1	2	3	4	5	6	7
钩码的拉力F/N	0	0.5	1	1.5	2	2.5	3
弹簧的长度L/cm	2	3	4	5	6	7	8