1. The problem statement, all variables and given/known data So, we are considering a spring-mass system, in which the mass at the end of the spring, M, is comparable to the mass of the spring, m. Using Newtons laws, I have to calculate, how significant the mass of the spring is. 2. Relevant equations Mass at the end of the spring, M. Mass of the spring, m. Spring constant, k. Newtons second law, and Hooke's law. 3. The attempt at a solution Actually, I have tried quite lot different approaches, but they don't seem to give me anything useful. My latest attempt was to take a differential piece of mass of the spring, and calculate it's acceleration, in hope of getting something which i could integrate, but it didn't seem to work out. I was asked this question by a high school student, whom I have to help writing a larger assignment. I solved this problem rather easily using Lagrangian mechanics, but this is not available to the student, so I have to do it with Newtonian mechanics, which doesn't seem too easy. I really appreciate any help I can get.