The weight of an aero plane flying is balanced by
Correct answer: B. Force due to the pressure difference between the upper and lower surfaces of the wings, created by different air speeds
- A. Upthrust of the air, which is equal to the weight of the air having the same volume as the plane
- B. Force due to the pressure difference between the upper and lower surfaces of the wings, created by different air speeds
- C. Vertical component of the thrust created by air currents striking the surface of the wings
- D. Force due to the reaction of gases ejected by the revolving propeller
Explanation
The correct answer is the force due to the pressure difference between the upper and lower surfaces of the wings, created by different air speeds. This is a manifestation of Bernoulli's principle, where faster air flow over the top surface of the wing reduces pressure compared to the slower air flow below, creating lift that balances the airplane's weight. Option A incorrectly applies the concept of buoyancy to airplanes, whereas Option C confuses thrust with lift. Option D describes thrust from propellers, which is unrelated to the lift needed to balance weight.
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About Fluid Dynamics
Fluid flow is described through speed, pressure and density, including steady flow and the equation of continuity for conserving mass. Bernoulli's equation relates pressure, speed and height, while fluid drag and terminal velocity explain why a falling object eventually moves at constant speed when drag balances its weight.
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