Hi guys! I have a small problem about a... problem My physics lecturer gave us a homework task (see below), which is the same as one problem in Paul Tipler's book of Physics (for scientists and engineers, fourth edition) [page 434, task 36]. In the book it is said: "An object of mass m is supported by a vertical spring...". However, my teacher changed just the word "object" with "weightlifter". Everything else is the same! Did he do that intentionally, or just to mislead us? Moreover, he provided a tip: "Don't neglect the gravitational force!" I got a result, saying the mass is 1.5 kg!!! Can someone check if everything is correct, because I will vomit! :yuck: It took me three days to search for a different solution, but all the results I got were = 1.5 kg! TASK: A "weightlifter" of mass m is supported by a vertical spring (k=1800 N/m). When pulled down 2.5 sm from equilibrium and released, it oscillates at 5.5 Hz. Find m! Thanks in advance!