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Describe what happens : (1) Hold the short edge of a paper strip (2″ × 6″) up to your lipsthe strip slanting downward over your fingerand blow over the top of the strip. (2) Hold two strips of paper up to your lips, separated by your fingers and blow between the strips. |
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Answer» (1) The air stream over the top surface travels faster than the air stream below the paper strip. This decreases the air pressure above the strip relative o that below. This produces an aerodynamic lift in accordance with Bernoulli’s principle and the paper strip will lift up. (2) Air passing between the paper strips flows in a narrower channel and, in accordance with Be rnoulli’s principle, must increase its speed, causing the pressure between them to drop. This will pinch the two strips together. |
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