1. The problem statement, all variables and given/known data http://desmond.imageshack.us/Himg812/scaled.php?server=812&filename=quesq.jpg&res=medium [Broken] 2. Relevant equations F = ma, F = -kx, SHM equations 3. The attempt at a solution Here's the diagram they've done for part (b). http://desmond.imageshack.us/Himg844/scaled.php?server=844&filename=ansr.jpg&res=medium [Broken] I'm not understanding why the 6mkv force is shown acting upwards; surely if the string is going to move up, and the water is a resistive force, then it would act downwards? And why is the acceleration downwards? I thought it would accelerate towards the point where it reaches (x+e) where the particle would be at maximum velocity, or am I thinking of springs? Thanks.