Question

An aeroplane stays in the air because:

• A. The velocity of air above the wings is less than the velocity of air below the wings.
• B. The velocity of air below the wings is less than the velocity of air above the wings.
• C. The velocities of the air above and below the wings are perfectly balanced.
• D. The wings generate a thrust by expelling mass at low velocities.

Answer 1

The correct option is B The velocity of air below the wings is less than the velocity of air above the wings.

The wings of a plane are designed in an aerofoil shape and can be slightly controlled. When the plane is flying, the velocity of air above the wings will be more than the velocity of air below. So, according to Bernoulli's principle, the pressure below the wings will be more than the above region. This results in a force in the upward direction, which balances the weight of the plane.