Hello, A was just helping my younger brother review some mechanics when I tried to explain how friction will cause the oscillations to eventually die out as the frequency keeps decreasing. So while analysing the force diagram and assuming that the frictional force is proportional to negative of the first degree of velocity, it turned out that if the mass spring system is moving from left to right, after it crosses the equilibrium position the spring force and frictional force will both be pointing to the left. F= -kx -Friction What I'm trying to say is since this is boosting the restoring force, it will be just like a stiffer spring, hence faster oscillations. The same explanation occurs for the other direction of motion. Of course when particle has already reached either ends and returning to the equilibrium point then then F= -kx + Friction (increasing the period as one would expect). The thing is how then does the system come to rest if it is slowed at one end and sped up at the other. Obviously I know that the my thinking is flawed but I cannot find where !! Please look at it.