  A weak spring is connected at one end to a rotor turning at constant angular
velocity. The spring extends to a stretched length as determined by the spring
mass, rest length, spring constant, rotor radius and rotor angular velocity.
When released from the rotor, the inner end of the spring pulls away as
expected, causing a wave to travel down the spring as it collapses. During this
time interval, the outer end of the spring continues to move along its original
circular path in uniform circular motion, as if the spring were still connected
to the rotor. This is analogous to the effect of a hanging Slinky released from
rest whose bottom end remains at a fixed position above the ground until a wave
from the top of the Slinky reaches the bottom of the Slinky. Values from a
numerical model and measurements from video analysis show that upon release the
inner end travels along a circle of similar radius as the outer end. The effect
appears as a series of alternating semi-circles. In addition, the simulation
and data agree that (1) the spring extension and drag angle increase with the
angular velocity of the rotor; (2) the droop angle decreases with angular
velocity of the rotor; (3) the collapse time and bend angle of the collapsing
spring are independent of the angular velocity.
