In a demonstration of elastic behavior, five helical spiral springs of identical shape but painted in different colors were shown to elastically extend by different amounts when loaded with a 100, 200 and 500 gm weight. What is the cause? What has Hooke’s law to do with this? Please explain.
The springs were made of different metals and therefore their elastic moduli were different. Specifically, according to Hooke's law, tensile stress = tensile strain times Young's modulus. For the same load, ie. same stress, the elongation, ie. strain, is inversely proportional to the elastic modulus.