题干

小明在选用弹簧测力计的过程中,发现测量大小相同的力时,用不同规格的测力计,弹簧伸长的长度不一样。对哪些因素会影响弹簧的伸长量,小明有三种猜想:

猜想1:制造弹簧所用的材料可能影响弹簧的伸长量。

猜想2:弹簧的原长可能影响弹簧的伸长量。

猜想3:弹簧的粗细可能影响弹簧的伸长量。

小明为探究自己的猜想,设计出一个实验方案:

①将一根弹簧剪成长度不同的两根,测出两根弹簧的初始长度L1、L2

②如图所示,固定弹簧的一端,用大小相同的力拉弹簧,测出两根弹簧的对应长度

改变拉力的大小,重复实验步骤①②,记录实验数据。

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