(b) The weight of the car shown in Figure Q2(a) is 9.8 kN when it is fully loaded by passengers and 2.4 kN when it is empty. The effective spring constant is given as 2.5 kN/m and the damping coefficient is 2 kNs/m. Given the speed of the car is 96 km/h, the road is assumed to be sinusoidal with a period of 4.88 m and an amplitude of X m, determine, i. ii. iii. iv. V. the natural frequency (wn) when the car is fully loaded and when the car has no passengers (the car is empty), [CO2/PO2/C4] (2 marks) the excitation frequency (w), [CO2/PO2/C4] (2 marks) the displacement transmissibility ratio, X/X, when the car has no passengers (the car is empty), [CO2/PO2/C4] (2 marks) the displacement transmissibility ratio, X/X1, when the car is fully loaded, and [CO2/PO2/C4] (2 marks) the amplitude ratio of the car in fully loaded and empty conditions. k S m 14 m 1 Cycle Figure Q2(a) (c) The suspension spring of a tractor shown in Figure Q2(c) is compressed by 120 mm due to the weight of the tractor. Determine the critical speed of the tractor as it travels at a constant speed over a road whose response profile can be approximated by a sine wave with an amplitude of 75 mm and a wavelength of 14 m (do not consider damping). [CO2/PO3/C4] (5 marks) X Figure Q2(c) X [CO2/PO2/C4] (2 marks) W O