Quirkles - Jazzy's Big Breath
Friday, Jul 10, 2009 @07:40am CDT
 Jazzy's Big Breath
Just how “windy” are you?
objective: To demonstrate Bernoulli’s Principle
procedure:Tie a knot in one end of the bag and leave the other end open to blow into (the bag has two open ends). Ask the children how many breaths they think it will take to blow up the bag.
Record the answers. Explain that you can blow up the bag in one breath. Have a partner assist you by holding on to the closed end of the bag. Hold the open end of the bag approximately ten inches away from your mouth. Using only one breath, blow as hard as you can into the bag. Quickly seal the bag with your hand so none of the air escapes. Tie a slip knot in the end of the bag, or let the air out and try again.
conclusion: The long bag quickly inflates because air from the atmosphere is drawn into the bag from the sides, along with the stream of air from your lungs. In 1738, Daniel Bernoulli observed that a fast moving stream of air is surrounded by an area of low atmospheric pressure. When you blow into the bag, air in the atmosphere is drawn into the long bag at the same time that you are blowing into the bag.
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