An electric motor and its base have a combined mass of M = 12 kg Each of the four springs attached to the base has a stiffness k = 480 kN/m and a viscous damping coefficient c. The unbalance of the motor is equivalent to a mass m = 0.005 kg located at the distance e = 90 mm from the center of the shaft. When the motor is running at ω = 400 rad/s, its steady-state amplitude is 1.8 mm. Determine
(a) the damping coefficient of each spring; and
(b) the phase angle between the displacement of the motor and ωt
