1. The problem statement, all variables and given/known data An elastic string is attached to A on a horizontal plane and a mass is attached to the other side of the rope.Then the rope is pulled to C and release.It engage in SHM from C to B and D to E and so on natural length = l extension = a max end points = E & C periodic time of the SHM ? Center if oscillation ? amplitude of the SHM ? 2. Relevant equations 3. The attempt at a solution I know that it doesn't engage SHM from B to D as the rope has not exceeded its natural length at that time...From B to D it travels at a constant velocity...As the periodic time of the oscillation is the time that it takes to complete an oscillation,I think it must be 2tEC,but not sure maybe its 2(tED+tBC). Actually I don't have an idea about the center if oscillation whether its A or B and D. And also amplitude.I think its DE or BC not AE as the SHM happens in only that area..