Why do you hear a glugging sound when you pour a liquid out of a bottle by holding it upside down?
Asked by: Matt
That is just air rushing in to fill the space left above
the liquid. As the liquid leaves, the pressure above it
decreases until the larger atmospheric pressure outside
the bottle forces air in to equalize pressure.
You'll notice that if you pour out the liquid gently,
leaving an open space between it and the top of the bottle
opening, air can enter more gradually, without the
Answered by: Paul Walorski, B.A. Physics, Part-time Physics Instructor
'I have deep faith that the principle of the universe will be beautiful and simple.'