Lift & Bernoulli Principle

• Bernoulli Principle 


  An additional force can be created by a pressure gradient as a result of differing air velocities. Creation of an additional lift force in flight is possible based on the shape of a projectile.
• The overall effect of the principle to increase the projectile ' hang time ' in the air, increasing the overall horizontal distance covered.
• Lift force 


  An additional force created by a pressure gradient forming on opposing surfaces of an aerofoil moving through a fluid or the air.
• This shape is an aerofoil

  A) High velocity

  B) Low velocity

  C) Low pressure

  D) High pressure

  
• Aerofoil


  1. As the aerofoil moves through the air it forces the air to part.
  2. The air then flows around and behind the aerofoil at different velocities before meeting behind it at the same time.
• Aerofoil

  3. This results in a different air pressure above and below the aerofoil, resulting in additional force.

  4. The curved surface forces air to travel a greater distance and thus with GREATER velocity

  4. The flat surface allows air to travel a shorter distance and thus LOWER velocity.
• As velocity increases , pressure DECREASES , so a LOW pressure zone is created above the curved surface and a HIGH pressure zone is created below the flat surface.
• This pressure gradient creates an additional lift force.
• The angle of attack promotes an aerofoil.
• In the discus event the athlete has to turn the projectile into an aerofoil by releasing it at 17 degrees. This is known as the angle of attack.
• Discus flight diagrams

  A) decelerating

  B) non parabolic