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An airplane of mass 1.50 × 104 kg is in level flight, initially moving at 60.0 m/s. The resistive force exerted by air on the airplane has a magnitude of 4.0 × 104 N. By Newton’s third law, if the engines exert a force on the exhaust gases to expel them out of the back of the engine, the exhaust gases exert a force on the engines in the direction of the airplane’s travel. This force is called thrust, and the value of the thrust in this situation is 7.50 × 104 N. (a) Is the work done by the exhaust gases on the airplane during some time interval equal to the change in the airplane’s kinetic energy? Explain. (b) Find the speed of the airplane after it has traveled 5.0 × 102 m.
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