1. The problem statement, all variables and given/known data A mass m connected using elastic spring to the roof. the mass is rotating horizontaly. mass m= 0.6kg rate or spring constant (k) = 40 N*m-1 frequency= 1/2 sec-1 spring's equilibrium length is 0.8m The question is: what is the length (L) of the spring while the mass rotating? (earths gravity of course) 2. Relevant equations F(spring)= -kΔx F(gravity)=mg Fr= mω2r 3. The attempt at a solution What I did is: On y: Tsinθ=mω2r now r=L*sinθ And T = kΔx = k(L-0.8) ω = 2*pi*f = pi → k(L-0.8)*sinθ=mω2*L*sinθ →→ L=0.939 Now the problem is, that I believe that my colculation proves that gravity have no effect on the length of the spring, and I can hardly believe that, In fact Im almost sure that Im wrong. Hope you can help me find my mistake! thanks!