A jet aircraft is flying in a standard atmosphere at an altitude of 4,000 m at 900 km/hr. The frontal intake area of the jet engine is 0.80 m2. The engine exhaust area is 0.56 m2. The temperature of the exhaust gas is 120°C. Assume ideal fluid flow conditions at the exhaust section. Fuel flow to the engine is 10,000 kg/hr. At what speed (km/hr) will a stationary observer on the earth see the exhaust gas move away from the engine relative to the earth?