Aspring-mass system has a spring constant of 3 n/m. a mass of 2 kg is attached to the spring, and the motion takes place in a viscous fluid that offers a resistance numerically equal to the magnitude of the instantaneous velocity. if the system is driven by an external force of (15 cos 3t − 10 sin 3t) n, determine the steady state response. express your answer in the form r cos(ωt − δ). (let u(t) be the displacement of the mass from its equilibrium position at time t.)