The figure shows a simple model of a motor vehicle that can vibrate in the vertical direction while traveling over a rough road. The vehicle has a mass of 2000 kg. The suspension system has a spring constant of 400 kN/m and a damping ratio of 0.5. The vehicle speed is 15 km/hr. The road surface varies sinusoidally with an amplitude of Y-0.05 m and a wavelength of 6 m. Answer questions 7 and 8. 7. What is the ratio between the base excitation frequency and the natural frequency of the vehicle. A0.309 C. 0.516 E. 0.206 B. 0.119 D. 0.619 8. Determine the displacement amplitude of the vehicle due to this road. A. 63 mm C. 70 mm E. 52 mm B. 67 mm D. 55 mm 800 1 y(1)