A mass weighing 16 pounds stretches a spring 8/3 feet. The massis initially released from rest from a point 2 feet below theequilibrium position, and the subsequent motion takes place in amedium that offers a damping force that is numerically equal to 1/2the instantaneous velocity.
Find the equation of motion x(t) if the mass is driven by anexternal force equal to f(t) = 20 cos(3t). (Use g = 32 ft/s2 forthe acceleration due to gravity.)
