6. An airplane of mass 1.5 x 104 kg is moving at 60 m/s. The pilot then revs the engine so that the forward thrust by the engines becomes 7.5 x 104 N. If the force of air resistance is 4.0 x 104 N , find the speed of the airplane after it has traveled 800 m. Assume that the plane remains horizontal throughout this flight.

The speed of the airplane after it has travelled 800 meters is approximately 85.632 meters per second.

Explanation:

From statement, we obtain the equation of equilibrium associated with the airplane:

(1)

Where:

- Thrust force from engines, measured in newtons.

- Force of air resistance, measured in newtons.

- Mass of the airplane, measured in kilograms.

- Net acceleration of the airplane, measured in meters per square second.

If we know that , and , then the net acceleration of the airplane is:

Lastly, the final speed of the airplane is calculated by the following kinematic equation:

(2)

Where:

- Travelled distance, measured in meters.

, - Initial and final speeds of the aircraft, measured in meters per second.

If we know that , and , then the final speed of the aircraft is:

The speed of the airplane after it has travelled 800 meters is approximately 85.632 meters per second.

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