The disk has mass m, radius r and moment of inertia IG = mr2/2. The spring constant is k = mg/r. The disc is released from rest when the spring is unscratched, and disk rolls without slipping. Let x be the position of the centre of the disc, measured down the incline from the initial position.
a) Find the velocity of the centre of the disc as a function of x.
b) Find the value of x where the velocity is maximum.
