1. The problem statement, all variables and given/known data Investigating the effect of mass on the period of oscillation. This experiment is about SHM of a floating cylinder, and the theory is explained in this website: http://physics.stackexchange.com/questions/64154/shm-of-floating-objects Also, I'm attaching a diagram of my experimental setup. (x is the displacement of the cylinder under water) 2. Relevant equations Buoyant force acting on the cylinder, F=Vρg=Axρg As Newton's second law states that F=ma, a=-Axρg/m Since a is directly proportional to -x, this fulfils the condition for SHM. a=ω^2x, and ω=2∏/T therefore a=(4∏^2)x/T^2 -Axρg/m=(4∏^2)x/T^2 From the derivation above, it can be concluded that 1/m is directly proportional to 1/T^2, and therefore m is proportional to the square of period. 3. The attempt at a solution I tried to perform the above experiment. The cylinder does bob up and down in the water, but it does not perform SHM. First of all, the amplitude keeps decreasing, but I have no idea what is the source of energy loss. Besides, the correlation between m and T^2 is also not directly proportional. Does anyone have an idea what's the error in this experiment?