Aim: To demonstrate Bernoulli's Principle.
1. Drawing pin
2. Cardboard piece
3. Cotton reel
Procedure: Insert a drawing pin through the centre of a cardboard piece and place a cotton reel over the point of the pin. Then hold the cotton reel in one hand and the card in the other, and blow air downward or upward through it and release the card. The cardboard does not fall but remains stuck to the cotton reels as long as you blow air, his is due to Bernoulli's principle.
When air moves fast parallel to the top surface of any body pressure of the air above the surface is lesser than pressure below that surface. Common Applications of Bernoulli's Principle
Bernoulli Principle places predominant role in real life as you come across followed by… Airflight
One of the most common everyday applications of Bernoulli's principle is in airflight. The main way that Bernoulli's principle works in air flight has to do with the architecture of the wings of the plane. In an airplane wing, the top of the wing is soomewhat curved, while the bottom of the wing is totally flat. While in the sky, air travels across both the top and the bottom concurrently. Because both the top part and the bottom part of the plane are designed differently, this allows for the air on the bottom to move slower, which creates more pressure on the bottom, and allows for the air on the top to move faster, which creates less pressure. This is what creates lift, which allows planes to fly. An airplane is also acted upon by a pull of gravity in which opposes the lift, drag and thrust. Thrust is the force that enables the airplane to move forward while drag is air resistance that opposes the thrust force.
*A bird's wing is curved along the top, so that when air passes over the wing and divides, the curve forces the air on top to travel a greater distance than the air on the bottom. The tendency of airflow, as noted earlier, is to correct for the presence of solid objects and to return to its original pattern as quickly as possible. Hence, when the air hits the front of the wing, the rate of flow at the top increases to compensate for the greater distance it has to travel than the air below the wing. And as shown by Bernoulli, fast-moving fluid exerts less pressure than slow-moving fluid; therefore, there is a difference in pressure between the air below and the air above, and this keeps the wing aloft.
A boomerang flies through the air on a plane perpendicular to the ground, rather than parallel. Hence, any thrower who properly knows how tosses the boomerang not with a side-arm throw, but overhand. As it flies, the boomerang becomes both a gyroscope and an airfoil, and this dual role gives it aerodynamic lift. Like the gyroscope, the boomerang imitates a top; spinning keeps it stable. It spins through the air, its leading wing (the forward or upward wing) creating more lift than the other wing. As an airfoil, the boomerang is designed so that the air below exerts more pressure than the air above, which keeps it airborne.
Photograph of Australian-Aboriginal Boomerangs
HOW TO THROW A BOOMERANG(1) Hold one end of the Boomerang with the flat side to your palm, and the other end facing the direction in which you will throw it. Tilt off vertical as shown, typically about 20°.
(2) Face directly into the wind, then turn 50° to the right of the wind. Raise the Boomerang above your right shoulder and aim towards the sky, about 30° above horizontal.
(3) Release with a spinning motion as the Boomerang leaves your hand.
*Another very early example of a flying machine using Bernoulli's principles is the kite, which first appeared in China...