On Apr 10, 10:00 pm, "Harry K" wrote:

Poor example. The balloon expands when blown up and contracts when
able thus maintaining the pressure.

Harry K-

Which is exactly what the hose does. The volume of expansion involved,
however, is obviously much less; but that makes no difference to the
pressure. It's like a tiny capacitor vs. a big capacitor, for the
electronically inclined; both will charge up to the same voltage.