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Question 1 [20] The centre of gravity of a vehicle shown in Figure 1 is 800 mm from the surface of the road and 1.5 m from the rear wheels. The wheelbase is equal to 2 m. The coefficient of friction between the surface of the road and the front driving wheel is equal to 0.25. When accelerated from rest, this vehicle can reach an acceleration of (a m/s2) in 5 seconds. Whereas the vehicle engine speed is 250 rpm. If the vehicle has wheel radius of 250 mm, calculate the speed ratio of the first pair of gears selected in gear box. The front wheel shafts are directly connected to the output shaft of the gear train of the vehicle. Whereas the engine is connected to the input shaft of the gear box. 800 mm 1.5 m Figure 1: Vehicle Question 2. [10] The vehicle shown in Figure 1 consist of a manual power transmission with its first pair of gears, which are meshed has a module of 3 mm. The gears have pressure angle of 20°. The diameter of the pinon is 54 mm and addendum of each gear is 4 mm. Use the speed ratio calculated in question 1 to compute the contact ratio of the first pair of gears.