The 20-kg cylinder is released at the position shown and falls onto the nonlinear spring....

The 20-kg cylinder is released at the position shown and falls onto the nonlinear spring. In terms of the stretch S of the spring, its potential energy is  where k = 3000 N/m and q = 4000 N/m3. What is the velocity of the cylinder when the spring has been compressed 0.5 m?