1. The problem statement, all variables and given/known data I am trying to derive the formula for simple harmonic motion of a mass hanging on a spring. I understand the derivation for the situation when the mass and the spring are on an horizontal table. Then I go about deriving the same formula for the situation when a mass is hanging on a spring and I can't seem to get rid of the gravitational force components (F=m*g). 2. Relevant equations The picture describes my problem very well. http://prntscr.com/4koogs I can't get rid of the m*g!! 3. The attempt at a solution I'm very stuck. I know you guys aren't supposed to hand out answers but this is a matter of understanding the fundamental I would really like a good explanation. Thanks in advance!