Unit 2 Water and Weather - Spokane Public Schools

Chapter 5 ActivityOur atmosphere and golf ballsBernoulli's PrincipleIn addition to providing us with air to breathe, the air in ouratmosphere is useful for playing sports, travelling, and allsorts of things. Because of air and how it flows aroundobjects, a baseball pitcher can throw a “sinker,” an airplanecan fly, and a golf ball can soar for long distances.A short history of golf ballsIn the 1840's, a golf ball was madefrom the heated and molded partsof a Malaysian tree—the guttaperchagum tree. They were calledgutties. Golf players at the timerealized that old gutties with nicks(little dents or scratches) wentfurther than new ones. So, golfersstarted to nick the gutties onpurpose. In the early 1900's, balls were made of rubber andcoated with a latex. Circular depressions called dimples weremade in the balls. By 1930, a standard weight and size wasestablished for golf balls and approximately 400 dimpleswere put on each ball.What is Bernoulli’s Principle?The Bernoulli’s principle states that as air moves faster itspressure decreases. If a golf ball were smooth, air would flowover it at the same speed at the top and bottom. Because ofthe dimples and the backspin caused by hitting the ball withthe golf club, the air flowing over the top is moving fasterthan the air flowing under the ball. The faster air creates alow pressure so the ball experiences a “lift.” Bernoulli’sPrinciple was developed by Daniel Bernoulli, a Swissmathematician and scientist. Now, try to create Bernoulli’sPrinciple using three methods.Materials(A) Cheeseball snack food and bendable straw, (B) ping-pongball and blow dryer, and (C) paper strip (3 inches 9 inches)What you will doA: Put the bendable straw in yourmouth with the short section bent ata ninety degree angle up into the air.Place the cheeseball on the end of thestraw. Blow through the straw. Canyou get the cheeseball to besuspended in the air above thestraw? Keep trying. It can be done.B: Use a blow dryer and ping pongball for the same effect. Hold theblow dryer up vertically so that theball can be supported by the air flow.C: Hold the paper strip with your hand so that the 3 inchside is just below your lips and the length of the paper stripis hanging below your lips. Blow over the paper strip.Applying your knowledgea. Explain how the three activities worked using Bernoulli'sPrinciple. You may diagram your answer if you want.b. One of the diagrams (below) represents a baseball calleda “sinker” thrown by a pitcher. The other represents agolf ball. High pressure (H) and low pressure (L) regions,and the direction of air currents around the balls areindicated. Identify which ball is the “sinker” and whichball is the golf ball. Explain your reasoning. Hint:Identify where the air is flowing faster over each ball.118