The 4-kg circular disk is attached to three springs, each spring having a stiffness k = 18...

The 4-kg circular disk is attached to three springs, each spring having a stiffness k = 180 N/m. If the disk is immersed in a fluid and given a downward velocity of 0.3 m/s at the equilibrium position, determine the equation which describes the motion. Consider positive displacement to be measured downward, and that fluid resistance acting on the disk furnishes a damping force having a magnitude F = (60|v|) N, where v is the velocity of the block in m/s.