A spring with spring constant k is attached to mass M. The spring is horizontal and mass M sits on a horizontal frictionless table. On the side of mass M opposite to the spring a cord is attached that runs over a pulley (which you may take to be ideal: zero mass, zero moment of inertia, and frictionless). The cord is attached to a hanging mass m.
Find the equilibrium position of the masses. (That means: How far does the spring stretch from its un-stretched length?)