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Procedure:
Hold one straw vertically in the water and the other horizontally
so that the ends are close together. By blowing air into the
horizontal straw, the student causes water to get sucked up
and spray out of the vertical straw. This usually takes a little
moving around of the blowing straw.
Explanation: The air
from your breath curves around the top of the vertical straw.
The streamline curvature allows the flow to sustain a pressure
difference between ambient and at the straw tip. The faster
you blow, the lower the pressure and therefore the greater the
force to pull the flow up the straw. |
