2 B
Conundrum 31
Balloons
on a hose
Cube
Conundrum
Two balloons are attached to either end of a hose that is pinched shut.
One balloon is almost fully inflated, the other only slightly.
What will happen when the hose is released?
a) The big balloon inflates the smaller one until they are the same size
b) The small balloon inflates the large one
c) Nothing
Solution
b) The smaller balloon inflates the larger one
Law of Laplace
The smaller balloon inflates the larger one. This unexpected result is due to the
counterintuitive relationship between a balloon’s radius (or bubble) and its internal air
pressure. While it seems logical that the internal pressure of a fully inflated balloon
would be higher, because the rubber is more stretched, the opposite is actually true.
The smaller balloon has the greater internal pressure and therefore inflates the larger
balloon. The same effect explains why smaller soap bubbles are more perfectly
spherical than larger bubbles, and why very large bubbles are so wobbly. The
relationship between the internal pressure, radius and tension in pressure vessel is
often referred to as the Law of Laplace, particularly in medicine. It accounts for,
among other things, the bursting of aneurysms.
Conundrum 31 – Balloons on a Hose | Page 1
© ABC Science Online 2010
Balloons on a Hose
Balloons on a Hose
a) The big balloon inflates the smaller one until they
are the same size
b) The small balloon inflates the large one
c) Nothing
Write your name and answer on the back
a) The big balloon inflates the smaller one until they
are the same size
b) The small balloon inflates the large one
c) Nothing
Write your name and answer on the back
Write your name and answer on the back
Two balloons are attached to either end of a hose that
is pinched shut. One balloon is almost fully inflated, the
other only slightly. What will happen when the hose is
released?
a) The big balloon inflates the smaller one until they
are the same size
b) The small balloon inflates the large one
c) Nothing
a) The big balloon inflates the smaller one until they
are the same size
b) The small balloon inflates the large one
c) Nothing
Two balloons are attached to either end of a hose that
is pinched shut. One balloon is almost fully inflated, the
other only slightly. What will happen when the hose is
released?
Balloons on a Hose
Write your name and answer on the back
Write your name and answer on the back
Two balloons are attached to either end of a hose that
is pinched shut. One balloon is almost fully inflated, the
other only slightly. What will happen when the hose is
released?
Write your name and answer on the back
a) The big balloon inflates the smaller one until they
are the same size
b) The small balloon inflates the large one
c) Nothing
a) The big balloon inflates the smaller one until they
are the same size
b) The small balloon inflates the large one
c) Nothing
Two balloons are attached to either end of a hose that
is pinched shut. One balloon is almost fully inflated, the
other only slightly. What will happen when the hose is
released?
Two balloons are attached to either end of a hose that
is pinched shut. One balloon is almost fully inflated, the
other only slightly. What will happen when the hose is
released?
Two balloons are attached to either end of a hose that
is pinched shut. One balloon is almost fully inflated, the
other only slightly. What will happen when the hose is
released?
Balloons on a Hose
Balloons on a Hose
Balloons on a Hose
Student Answer Form – Blackline Master
Conundrum 31 – Balloons on a Hose | Page 2
© ABC Science Online 2010