3. 3 Abgass of 20 kg is suspended from a spring which deflects 3.0 cm under the load. Calculate the frequency of free vibration and verify that a viscous damping force amounting to approximately 725 Nm/rad at a speed of 1 m/sec. is just sufficient to make the motion aperiodic. If when damped to this extent, the body is subjected to a disturbing force of value 50Coswt making 4 cycles/sec. find the amplitude of the ultimate motion.