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UNSW : UNSW Atmosphere Study Guide
Atmosphere Study Guide 40 BACKGROUND INFORMATION Bernoulli’s Principle states that there is less pressure with fast moving air than with slow moving air. Daniel Bernoulli was a Swiss mathematician who published his famous discovery about the pressure of slow and fast moving air in the 1730s. His principle works for anything that flows such as water particles and air particles. In aerodynamics, Bernoulli’s Principle is used to help lift and keep aeroplanes off the ground. Due to the shape of the wings the air has to travel faster over the top of the wing creating less pressure, this lifts the wing and the plane. In this experiment we will discover how blowing (fast moving) air between two strips of paper creates less pressure and moves the two pieces of paper together. AIM To find out how far two sheets of paper can be parted and still be affected by Bernoulli’s Principle. MATERIALS • Two strips of 8 cm by 21 cm paper (21 cm is the width of an A4 sheet of paper) • A retort stand and clamp • Sticky tape • A millimetre ruler • A hairdryer with a thin nozzle (optional) METHOD 1. Attach the strips of paper to the retort stand so that they are facing each other and are positioned 3 cm apart. The strips of paper should be parallel, i.e. 3cm apart all the way down, like in the diagram below. 2. Now blow air down between the two strips of paper with your breath or a hairdryer, and have a partner note that the two strips of paper come together. If the paper does not come together, check that they are able to move and are not stuck to the retort stand in a way that prevents them from swinging back and forth. Also check that the air is being blown directly down between the middle of the two strips and right at the space where the paper starts (i.e. not too far above the paper) 3. Have your lab partner blow between the two strips of paper while you watch the two strips of paper come together. If you have a hairdryer with a thin nozzle that can blow an even draft between the two pieces of paper you might want to use that instead. 4. Practice blowing with even breaths each time till you are confident you can blow at the same strength each time. 5. Now move the pieces of paper away from each other 1 cm so that they are now 4 cm apart. Experiment 2 DISCOVERING BERNOULLI’S PRINCIPLE Elaborate side view of two trips of paper hanging down air is blown directly between the two strips of paper retort stand and clamp