A car and its suspension system are idealized as a damped spring-mass system, with natural frequency 0.5Hz and damping ration of 0.2. Suppose the car drives at speed "v" over a road with sinusoidal roughness. Assume the roughness wavelength is 10m, and its amplitude is 20cm. At what speed does the maximum amplitude of vibration occur, and what is the corresponding vibration amplitde.