Answer
(a) The air flow above the paper decreases the pressure there. This creates a pressure difference, and a lift force results. (b) The egg is kept aloft by the pressure of the air coming out of the end of the tube. If the egg moves to one side （partially out of the stream）, there is then a slower flow speed around the outside of the egg and thus a larger pressure on that side. This creates an inward pressure difference that forces the egg back to midstream.
Work Step by Step
(a) The air flow above the paper decreases the pressure there. This creates a pressure difference, and a lift force results. (b) The egg is kept aloft by the pressure of the air coming out of the end of the tube. If the egg moves to one side （partially out of the stream）, there is then a slower flow speed around the outside of the egg and thus a larger pressure on that side. This creates an inward pressure difference that forces the egg back to midstream.
