| |
Experimental
Several
wheels are provided each of which has a bearing of a different
type. One bearing may have its
'tightness' changed by rotating the
end caps, the others are all of fixed tightness but with a plane sleeve
bearing,
a needle race, or a ball race. The wheels and bearings are held in the
forks and can be rotated by hand to various speeds that can be measured using
the attached tachometer and the computer data acquisition system. The decrease
of the rotational speed as a function of time provides information about
the rate of dissipation of the rotational kinetic energy of the wheel due to
the various drag forces acting on it, one of which will be due to the bearing.
With
a given wheel, spin it up and use the instruments to measure the
rotation rate of the wheel as a
function of time. Measure the rotation rate
until it decreases to zero. Plot the data in Excel. Repeat the measurement
after changing the moment of inertia of the wheel-weight system by sliding
the weights towards the wheel rim. Measure the weight of the wheel and weights
and the radial distance of the weights from the wheel axis. This information
will be used to compute the moment of inertia of the wheel-weight system.
Select two other bearing types and repeat the measurements with these systems.
|
|
