Description (from Leybold):
"Maxwell's wheel is used to demonstrate the forces of inertia as
well the conversion of potential energy to kinetic energy and back again
to potential energy.
The wheel is approximately 130 mm in diameter and has a mass of 428 grams.
It is fitted on an axel protruding 60 mm on each side. The diameter of
the axel is 6 mm. Moreover the axel is bored at each end and suspended
by approximately 45 cm long strings. One of the two suspension points
can be adjusted by means of a knurled-head screw."
Conservation of Energy
If it intended merely to demonstrate the conservation of energy and not
the forces of inertia, it suffices simply to set up the apparatus on it's
stand without the balance. In order that the wheel can move up and down
a number of times it is important that the axel is suspended exactly horizontal
and that the strings are wound on uniformly. To use, wind up the wheel
and axel on the strings and release. The wheel will repeatedly run down
the strings and return to nearly the original height. A small amount of
energy is "lost" to air friction, string friction, and into
the string at the reflection point (stretching).
To demonstrate the forces acting on the strings and the wheel, the assembly,
as described above should, be placed on an electronic balance. An obvious
but important point to note is that the balance reading equals the sum
of the stand mass and "force" exerted by the pair of strings
on the wheel and axel. Record the balance reading for the system at
rest. Now set the system into its "yo-yo" motion. Note the new
balance reading. The new reading is equal for both upward and downward
motion because both the linear and angular accelerations are constant
in magnitude for both directions of motion (velocity). This new reading
is about 1.6 g less than the static reading. This 1.6 g difference is
the decrease in upward "force" exerted by the string on the
axel during the acceration of the wheel and axel. The difference is small
because because the accelerations are low (wheel has a large I and the
torque on the axel is small).
Sample data for the system as presently configured:
mass of wheel and axel = 427.6 g
mass with stand, wheel at rest = 1596.9 g
mass with stand, wheel in motion = 1595.3 g.