Here is a homework problem that I believe is solved right. A child oscillates freely on a playground swing. It takes 2.5 seconds for the child to complete one full swing and return to the person that is pushing her. How long is the swing? This is how I solved for the answer. l = (980)(2.5)^2/4n^2 = 15112.83174 (the n stands for pi) then I took the square root of 15112.83174 to get 122.9342578 or 122.93 cm The next part of the problem I don't know what to do. A child twice as heavy sits on the same swing. What is his period of oscillation? How do you Know? I'm not real sure where I'm supposed to start with this problem.