My question is about a toy hovercraft - a balloon connected to a CD. I need to know about something. How does cross section of the pipe affect the time that the toy hovercraft hovers above the surface?
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The exact answer to your question can be found at http://hyperphysics.phy-astr.gsu.edu/hbase/ppois2.html#tub
There it shows that the flow rate goes as the 4th power of the radius of a pipe - so if you double the diameter, air will flow 16x faster.
The reason behind this is something I described in some detail in this earlier answer.