FIGURE 8.2.1. Oscillations of a simple
pendulum. If the energy is negative, the pendulum oscillates with an
amplitude and
the mean velocity is zero. If the energy is positive the motion consists
of a constant revolution modulated by an oscillation of the same
period. The angular velocity of this revolution may oe either
positive or negative.
and
the mean velocity 
is zero. If the energy is positive the motion consists
of a constant revolution modulated by an oscillation of the same
period. The angular velocity ![[Greek letter] omega](p542.10.jpg){kind=small}
of this revolution may oe either
positive or negative.